diff --git a/DESCRIPTION b/DESCRIPTION
index df33309f..03789f45 100755
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -67,7 +67,7 @@ Language: en-US
 BugReports: https://github.com/mjskay/tidybayes/issues/new
 URL: https://mjskay.github.io/tidybayes/, https://github.com/mjskay/tidybayes/
 VignetteBuilder: knitr
-RoxygenNote: 7.2.3
+RoxygenNote: 7.3.1
 LazyData: true
 Encoding: UTF-8
 Collate:
diff --git a/NAMESPACE b/NAMESPACE
index 799244a8..6f369c37 100755
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -20,6 +20,9 @@ S3method(epred_rvars,brmsfit)
 S3method(epred_rvars,default)
 S3method(epred_rvars,stanreg)
 S3method(fitted_draws,default)
+S3method(flip_aes,"function")
+S3method(flip_aes,character)
+S3method(flip_aes,data.frame)
 S3method(gather_emmeans_draws,default)
 S3method(gather_emmeans_draws,emm_list)
 S3method(get_variables,default)
diff --git a/NEWS.md b/NEWS.md
index b0543aa4..800f72d8 100755
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,6 +1,12 @@
 # tidybayes (development version)
 
-Buf fixes:
+New features:
+
+* Add support for `draw_indices` parameter in `spread_draws()` and
+  `gather_draws()`. (#323)
+
+
+Bug fixes:
 
 * Support for matrix columns in `nest_rvars()` and `unnest_rvars()`. (#316)
 
diff --git a/R/compare_levels.R b/R/compare_levels.R
index 5251d5d0..bc4147df 100755
--- a/R/compare_levels.R
+++ b/R/compare_levels.R
@@ -88,15 +88,7 @@ comparison_types = within(list(), {
 #' in the output `variable` column instead converting the unevaluated
 #' expression to a string. You can also use [emmeans_comparison()] to generate
 #' a comparison function based on contrast methods from the `emmeans` package.
-#' @param draw_indices Character vector of column names in `data` that
-#' should be treated as indices when making the comparison (i.e. values of
-#' `variable` within each level of `by` will be compared at each
-#' unique combination of levels of `draw_indices`). Columns in `draw_indices`
-#' not found in `data` are ignored. The default is `c(".chain",".iteration",".draw")`,
-#' which are the same names used for chain/iteration/draw indices returned by
-#' [spread_draws()] or [gather_draws()]; thus if you are using `compare_levels`
-#' with [spread_draws()] or [gather_draws()] you generally should not need to change this
-#' value.
+#' @template param-draw_indices
 #' @param ignore_groups character vector of names of groups to ignore by
 #' default in the input grouping. This is primarily provided to make it
 #' easier to pipe output of [add_epred_draws()] into this function,
diff --git a/R/flip_aes.R b/R/flip_aes.R
index 48451f33..34a2f5b9 100755
--- a/R/flip_aes.R
+++ b/R/flip_aes.R
@@ -29,17 +29,20 @@ flip_aes = function(x, lookup = flip_aes_lookup) {
   UseMethod("flip_aes")
 }
 
+#' @export
 flip_aes.character = function(x, lookup = flip_aes_lookup) {
   flipped = lookup[x]
   x[!is.na(flipped)] = flipped[!is.na(flipped)]
   x
 }
 
+#' @export
 flip_aes.data.frame = function(x, lookup = flip_aes_lookup) {
   names(x) = flip_aes(names(x), lookup = lookup)
   x
 }
 
+#' @export
 flip_aes.function = function(x, lookup = flip_aes_lookup) {
   name = force(deparse(substitute(x)))
   function(...) {
diff --git a/R/gather_draws.R b/R/gather_draws.R
index 1579455d..ac03d92e 100755
--- a/R/gather_draws.R
+++ b/R/gather_draws.R
@@ -10,13 +10,26 @@
 #' @importFrom dplyr bind_rows group_by_at
 #' @importFrom rlang enquos
 #' @export
-gather_draws = function(model, ..., regex = FALSE, sep = "[, ]", ndraws = NULL, seed = NULL, n) {
+gather_draws = function(
+  model,
+  ...,
+  regex = FALSE,
+  sep = "[, ]",
+  ndraws = NULL,
+  seed = NULL,
+  draw_indices = c(".chain", ".iteration", ".draw"),
+  n
+) {
   ndraws = .Deprecated_argument_alias(ndraws, n)
 
   draws = sample_draws_from_model_(model, ndraws, seed)
 
+  draw_indices = intersect(draw_indices, names(draws))
   tidysamples = lapply(enquos(...), function(variable_spec) {
-    gather_variables(spread_draws_(draws, variable_spec, regex = regex, sep = sep))
+    gather_variables(
+      spread_draws_(draws, variable_spec, regex = regex, sep = sep, draw_indices = draw_indices),
+      exclude = c(draw_indices, ".row")
+    )
   })
 
   #get the groups from all the samples --- when we bind them together,
diff --git a/R/spread_draws.R b/R/spread_draws.R
index 8df4e755..6455ea9d 100755
--- a/R/spread_draws.R
+++ b/R/spread_draws.R
@@ -202,6 +202,7 @@ globalVariables(c(".."))
 #' @param sep Separator used to separate dimensions in variable names, as a regular expression.
 #' @template param-ndraws
 #' @template param-seed
+#' @template param-draw_indices
 #' @template param-deprecated-n
 #' @return A data frame.
 #' @author Matthew Kay
@@ -232,13 +233,29 @@ globalVariables(c(".."))
 #' @importFrom dplyr inner_join group_by_at
 #' @rdname spread_draws
 #' @export
-spread_draws = function(model, ..., regex = FALSE, sep = "[, ]", ndraws = NULL, seed = NULL, n) {
+spread_draws = function(
+  model,
+  ...,
+  regex = FALSE,
+  sep = "[, ]",
+  ndraws = NULL,
+  seed = NULL,
+  draw_indices = c(".chain", ".iteration", ".draw"),
+  n
+) {
   ndraws = .Deprecated_argument_alias(ndraws, n)
 
   draws = sample_draws_from_model_(model, ndraws, seed)
 
+  draw_indices = intersect(draw_indices, names(draws))
   tidysamples = lapply(enquos(...), function(variable_spec) {
-    spread_draws_(draws, variable_spec, regex = regex, sep = sep)
+    spread_draws_(
+      draws,
+      variable_spec,
+      regex = regex,
+      sep = sep,
+      draw_indices = draw_indices
+    )
   })
 
   #get the groups from all the samples --- when we join them together,
@@ -260,7 +277,13 @@ spread_draws = function(model, ..., regex = FALSE, sep = "[, ]", ndraws = NULL,
 #' @importFrom dplyr mutate group_by_at
 #' @importFrom tidyr spread
 #' @importFrom rlang has_name
-spread_draws_ = function(draws, variable_spec, regex = FALSE, sep = "[, ]") {
+spread_draws_ = function(
+  draws,
+  variable_spec,
+  regex = FALSE,
+  sep = "[, ]",
+  draw_indices = c(".chain", ".iteration", ".draw")
+) {
   #parse a variable spec in the form variable_name[dimension_name_1, dimension_name_2, ..] | wide_dimension
   spec = parse_variable_spec(variable_spec)
   variable_names = spec[[1]]
@@ -268,7 +291,7 @@ spread_draws_ = function(draws, variable_spec, regex = FALSE, sep = "[, ]") {
   wide_dimension_name = spec[[3]]
 
   #extract the draws into a long format data frame
-  long_draws = spread_draws_long_(draws, variable_names, dimension_names, regex = regex, sep = sep)
+  long_draws = spread_draws_long_(draws, variable_names, dimension_names, regex = regex, sep = sep, draw_indices = draw_indices)
 
   #convert variable and/or dimensions back into usable data types
   #that were set on the model using recover_types
@@ -309,7 +332,14 @@ spread_draws_ = function(draws, variable_spec, regex = FALSE, sep = "[, ]") {
 ## dimension_names: a character vector of dimension names
 #' @importFrom tidyr spread separate gather
 #' @importFrom dplyr summarise_all group_by_at
-spread_draws_long_ = function(draws, variable_names, dimension_names, regex = FALSE, sep = "[, ]") {
+spread_draws_long_ = function(
+  draws,
+  variable_names,
+  dimension_names,
+  regex = FALSE,
+  sep = "[, ]",
+  draw_indices = c(".chain", ".iteration", ".draw")
+) {
   if (!regex) {
     variable_names = escape_regex(variable_names)
   }
@@ -326,7 +356,7 @@ spread_draws_long_ = function(draws, variable_names, dimension_names, regex = FA
     }
 
     variable_names = colnames(draws)[variable_names_index]
-    unnest_legacy(draws[, c(".chain", ".iteration", ".draw", variable_names)])
+    unnest_legacy(draws[, c(draw_indices, variable_names)])
   }
   else {
     dimension_sep_regex = sep
@@ -399,11 +429,11 @@ spread_draws_long_ = function(draws, variable_names, dimension_names, regex = FA
       # some dimensions were requested to be nested as list columns containing arrays.
       # thus we have to ADD CHAIN INFO then UNNEST, then NEST DIMENSIONS then SPREAD
       # 2. ADD CHAIN INFO
-      nested_draws[[".chain_info"]] = list(draws[,c(".chain", ".iteration", ".draw")])
+      nested_draws[[".chain_info"]] = list(draws[, draw_indices])
       # 3. UNNEST
       long_draws = unnest_legacy(nested_draws)
       # NEST DIMENSIONS
-      long_draws = nest_dimensions_(long_draws, temp_dimension_names, nested_dimension_names)
+      long_draws = nest_dimensions_(long_draws, temp_dimension_names, nested_dimension_names, draw_indices)
       # 1. SPREAD
       long_draws = spread(long_draws, ".variable", ".value")
     } else {
@@ -411,7 +441,7 @@ spread_draws_long_ = function(draws, variable_names, dimension_names, regex = FA
       # 1. SPREAD
       nested_draws = spread(nested_draws, ".variable", ".value")
       # 2. ADD CHAIN INFO
-      nested_draws[[".chain_info"]] = list(draws[,c(".chain", ".iteration", ".draw")])
+      nested_draws[[".chain_info"]] = list(draws[, draw_indices])
       # 3. UNNEST
       long_draws = unnest_legacy(nested_draws)
     }
@@ -429,7 +459,12 @@ spread_draws_long_ = function(draws, variable_names, dimension_names, regex = FA
 ## dimension_names: dimensions not used for nesting
 ## nested_dimension_names: dimensions to be nested
 #' @importFrom dplyr filter summarise_at
-nest_dimensions_ = function(long_draws, dimension_names, nested_dimension_names) {
+nest_dimensions_ = function(
+  long_draws,
+  dimension_names,
+  nested_dimension_names,
+  draw_indices = c(".chain", ".iteration", ".draw")
+) {
   ragged = FALSE
   value_name = ".value"
   value = as.name(value_name)
@@ -443,7 +478,7 @@ nest_dimensions_ = function(long_draws, dimension_names, nested_dimension_names)
   }
 
   long_draws = group_by_at(long_draws,
-    c(".chain", ".iteration", ".draw", ".variable", dimension_names) %>%
+    c(draw_indices, ".variable", dimension_names) %>%
       # nested dimension names must come at the end of the group list
       # (minus the last nested dimension) so that we summarise in the
       # correct order
diff --git a/R/tidybayes-package.R b/R/tidybayes-package.R
index 937839ff..ce408c65 100644
--- a/R/tidybayes-package.R
+++ b/R/tidybayes-package.R
@@ -1,6 +1,5 @@
 #' Tidy Data and 'Geoms' for Bayesian Models
 #'
-#' @docType package
 #' @name tidybayes-package
 #' @aliases tidybayes
 #'
@@ -34,4 +33,4 @@
 #' Wickham, Hadley. (2014). Tidy data. _Journal of Statistical Software_,
 #' 59(10), 1-23. \doi{10.18637/jss.v059.i10}.
 #'
-NULL
+"_PACKAGE"
diff --git a/R/ungather_draws.R b/R/ungather_draws.R
index 799ed7d1..aa337a06 100755
--- a/R/ungather_draws.R
+++ b/R/ungather_draws.R
@@ -14,7 +14,7 @@ globalVariables(c("..dimension_values"))
 ungather_draws = function(
   data, ..., variable = ".variable", value = ".value", draw_indices = c(".chain", ".iteration", ".draw"), drop_indices = FALSE
 ) {
-
+  draw_indices = intersect(draw_indices, names(data))
   variable_specs = enquos(...)
 
   if (length(variable_specs) == 0) {
diff --git a/R/unspread_draws.R b/R/unspread_draws.R
index b73cd624..fdcd0881 100755
--- a/R/unspread_draws.R
+++ b/R/unspread_draws.R
@@ -20,10 +20,7 @@ globalVariables(c("..dimension_values"))
 #' @param data A tidy data frame of draws, such as one output by `spread_draws` or `gather_draws`.
 #' @param ... Expressions in the form of
 #' `variable_name[dimension_1, dimension_2, ...]`. See [spread_draws()].
-#' @param draw_indices Character vector of column names in `data` that
-#' should be treated as indices of draws. The default is `c(".chain",".iteration",".draw")`,
-#' which are the same names used for chain, iteration, and draw indices returned by
-#' [spread_draws()] or [gather_draws()].
+#' @template param-draw_indices
 #' @param drop_indices Drop the columns specified by `draw_indices` from the resulting data frame. Default `FALSE`.
 #' @param variable The name of the column in `data` that contains the names of variables from the model.
 #' @param value The name of the column in `data` that contains draws from the variables.
@@ -62,6 +59,7 @@ globalVariables(c("..dimension_values"))
 #' @rdname unspread_draws
 #' @export
 unspread_draws = function(data, ..., draw_indices = c(".chain", ".iteration", ".draw"), drop_indices = FALSE) {
+  draw_indices = intersect(draw_indices, names(data))
   result =
     lapply(enquos(...), function(variable_spec) {
       unspread_draws_(data, variable_spec, draw_indices = draw_indices)
diff --git a/man-roxygen/param-draw_indices.R b/man-roxygen/param-draw_indices.R
new file mode 100755
index 00000000..232bdada
--- /dev/null
+++ b/man-roxygen/param-draw_indices.R
@@ -0,0 +1,5 @@
+#' @param draw_indices Character vector of column names that should be treated
+#' as indices of draws. Operations are done within combinations of these values.
+#' The default is `c(".chain", ".iteration", ".draw")`, which is the same names
+#' used for chain, iteration, and draw indices returned by [tidy_draws()].
+#' Names in `draw_indices` that are not found in the data are ignored.
diff --git a/man/compare_levels.Rd b/man/compare_levels.Rd
index 531f9b99..97b3984c 100755
--- a/man/compare_levels.Rd
+++ b/man/compare_levels.Rd
@@ -53,15 +53,11 @@ in the output \code{variable} column instead converting the unevaluated
 expression to a string. You can also use \code{\link[=emmeans_comparison]{emmeans_comparison()}} to generate
 a comparison function based on contrast methods from the \code{emmeans} package.}
 
-\item{draw_indices}{Character vector of column names in \code{data} that
-should be treated as indices when making the comparison (i.e. values of
-\code{variable} within each level of \code{by} will be compared at each
-unique combination of levels of \code{draw_indices}). Columns in \code{draw_indices}
-not found in \code{data} are ignored. The default is \code{c(".chain",".iteration",".draw")},
-which are the same names used for chain/iteration/draw indices returned by
-\code{\link[=spread_draws]{spread_draws()}} or \code{\link[=gather_draws]{gather_draws()}}; thus if you are using \code{compare_levels}
-with \code{\link[=spread_draws]{spread_draws()}} or \code{\link[=gather_draws]{gather_draws()}} you generally should not need to change this
-value.}
+\item{draw_indices}{Character vector of column names that should be treated
+as indices of draws. Operations are done within combinations of these values.
+The default is \code{c(".chain", ".iteration", ".draw")}, which is the same names
+used for chain, iteration, and draw indices returned by \code{\link[=tidy_draws]{tidy_draws()}}.
+Names in \code{draw_indices} that are not found in the data are ignored.}
 
 \item{ignore_groups}{character vector of names of groups to ignore by
 default in the input grouping. This is primarily provided to make it
diff --git a/man/reexports.Rd b/man/reexports.Rd
index 598cf0d3..3e178e21 100755
--- a/man/reexports.Rd
+++ b/man/reexports.Rd
@@ -137,7 +137,7 @@ These objects are imported from other packages. Follow the links
 below to see their documentation.
 
 \describe{
-  \item{ggdist}{\code{\link[ggdist:theme_ggdist]{axis_titles_bottom_left}}, \code{\link[ggdist]{curve_interval}}, \code{\link[ggdist]{cut_cdf_qi}}, \code{\link[ggdist:lkjcorr_marginal]{dlkjcorr_marginal}}, \code{\link[ggdist:student_t]{dstudent_t}}, \code{\link[ggdist:theme_ggdist]{facet_title_left_horizontal}}, \code{\link[ggdist:theme_ggdist]{facet_title_right_horizontal}}, \code{\link[ggdist:tidy-format-translators]{from_broom_names}}, \code{\link[ggdist:tidy-format-translators]{from_ggmcmc_names}}, \code{\link[ggdist]{geom_dots}}, \code{\link[ggdist]{geom_dotsinterval}}, \code{\link[ggdist]{geom_interval}}, \code{\link[ggdist]{geom_lineribbon}}, \code{\link[ggdist]{geom_pointinterval}}, \code{\link[ggdist]{geom_slab}}, \code{\link[ggdist]{geom_slabinterval}}, \code{\link[ggdist:ggdist-ggproto]{GeomDots}}, \code{\link[ggdist:ggdist-ggproto]{GeomDotsinterval}}, \code{\link[ggdist:ggdist-ggproto]{GeomInterval}}, \code{\link[ggdist:ggdist-ggproto]{GeomLineribbon}}, \code{\link[ggdist:ggdist-ggproto]{GeomPointinterval}}, \code{\link[ggdist:ggdist-ggproto]{GeomSlab}}, \code{\link[ggdist:ggdist-ggproto]{GeomSlabinterval}}, \code{\link[ggdist:scales]{guide_colorbar2}}, \code{\link[ggdist:scales]{guide_colourbar2}}, \code{\link[ggdist:point_interval]{hdci}}, \code{\link[ggdist:point_interval]{hdi}}, \code{\link[ggdist]{marginalize_lkjcorr}}, \code{\link[ggdist:point_interval]{mean_hdci}}, \code{\link[ggdist:point_interval]{mean_hdi}}, \code{\link[ggdist:point_interval]{mean_qi}}, \code{\link[ggdist:point_interval]{median_hdci}}, \code{\link[ggdist:point_interval]{median_hdi}}, \code{\link[ggdist:point_interval]{median_qi}}, \code{\link[ggdist:point_interval]{Mode}}, \code{\link[ggdist:point_interval]{mode_hdci}}, \code{\link[ggdist:point_interval]{mode_hdi}}, \code{\link[ggdist:point_interval]{mode_qi}}, \code{\link[ggdist]{parse_dist}}, \code{\link[ggdist:lkjcorr_marginal]{plkjcorr_marginal}}, \code{\link[ggdist]{point_interval}}, \code{\link[ggdist:student_t]{pstudent_t}}, \code{\link[ggdist:point_interval]{qi}}, \code{\link[ggdist:lkjcorr_marginal]{qlkjcorr_marginal}}, \code{\link[ggdist:student_t]{qstudent_t}}, \code{\link[ggdist:parse_dist]{r_dist_name}}, \code{\link[ggdist:lkjcorr_marginal]{rlkjcorr_marginal}}, \code{\link[ggdist:student_t]{rstudent_t}}, \code{\link[ggdist:scales]{scale_interval_alpha_continuous}}, \code{\link[ggdist:scales]{scale_interval_alpha_discrete}}, \code{\link[ggdist:scales]{scale_interval_color_continuous}}, \code{\link[ggdist:scales]{scale_interval_color_discrete}}, \code{\link[ggdist:scales]{scale_interval_colour_continuous}}, \code{\link[ggdist:scales]{scale_interval_colour_discrete}}, \code{\link[ggdist:scales]{scale_interval_linetype_continuous}}, \code{\link[ggdist:scales]{scale_interval_linetype_discrete}}, \code{\link[ggdist:scales]{scale_interval_size_continuous}}, \code{\link[ggdist:scales]{scale_interval_size_discrete}}, \code{\link[ggdist:scales]{scale_point_alpha_continuous}}, \code{\link[ggdist:scales]{scale_point_alpha_discrete}}, \code{\link[ggdist:scales]{scale_point_color_continuous}}, \code{\link[ggdist:scales]{scale_point_color_discrete}}, \code{\link[ggdist:scales]{scale_point_colour_continuous}}, \code{\link[ggdist:scales]{scale_point_colour_discrete}}, \code{\link[ggdist:scales]{scale_point_fill_continuous}}, \code{\link[ggdist:scales]{scale_point_fill_discrete}}, \code{\link[ggdist:scales]{scale_point_size_continuous}}, \code{\link[ggdist:scales]{scale_point_size_discrete}}, \code{\link[ggdist:scales]{scale_slab_alpha_continuous}}, \code{\link[ggdist:scales]{scale_slab_alpha_discrete}}, \code{\link[ggdist:scales]{scale_slab_color_continuous}}, \code{\link[ggdist:scales]{scale_slab_color_discrete}}, \code{\link[ggdist:scales]{scale_slab_colour_continuous}}, \code{\link[ggdist:scales]{scale_slab_colour_discrete}}, \code{\link[ggdist:scales]{scale_slab_fill_continuous}}, \code{\link[ggdist:scales]{scale_slab_fill_discrete}}, \code{\link[ggdist:scales]{scale_slab_linetype_continuous}}, \code{\link[ggdist:scales]{scale_slab_linetype_discrete}}, \code{\link[ggdist:scales]{scale_slab_shape_continuous}}, \code{\link[ggdist:scales]{scale_slab_shape_discrete}}, \code{\link[ggdist:scales]{scale_slab_size_continuous}}, \code{\link[ggdist:scales]{scale_slab_size_discrete}}, \code{\link[ggdist]{stat_ccdfinterval}}, \code{\link[ggdist]{stat_cdfinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_ccdfinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_cdfinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_dots}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_dotsinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_eye}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_gradientinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_halfeye}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_interval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_lineribbon}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_pointinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_slab}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_slabinterval}}, \code{\link[ggdist]{stat_dots}}, \code{\link[ggdist]{stat_dotsinterval}}, \code{\link[ggdist]{stat_eye}}, \code{\link[ggdist]{stat_gradientinterval}}, \code{\link[ggdist]{stat_halfeye}}, \code{\link[ggdist]{stat_histinterval}}, \code{\link[ggdist]{stat_interval}}, \code{\link[ggdist]{stat_lineribbon}}, \code{\link[ggdist]{stat_pointinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_sample_slabinterval}}, \code{\link[ggdist]{stat_slab}}, \code{\link[ggdist]{stat_slabinterval}}, \code{\link[ggdist:ggdist-deprecated]{StatDistSlabinterval}}, \code{\link[ggdist:ggdist-ggproto]{StatInterval}}, \code{\link[ggdist:ggdist-ggproto]{StatPointinterval}}, \code{\link[ggdist:ggdist-deprecated]{StatSampleSlabinterval}}, \code{\link[ggdist:ggdist-ggproto]{StatSlabinterval}}, \code{\link[ggdist]{theme_ggdist}}, \code{\link[ggdist:theme_ggdist]{theme_tidybayes}}, \code{\link[ggdist:tidy-format-translators]{to_broom_names}}, \code{\link[ggdist:tidy-format-translators]{to_ggmcmc_names}}}
+  \item{ggdist}{\code{\link[ggdist:theme_ggdist]{axis_titles_bottom_left}}, \code{\link[ggdist]{curve_interval}}, \code{\link[ggdist]{cut_cdf_qi}}, \code{\link[ggdist:lkjcorr_marginal]{dlkjcorr_marginal}}, \code{\link[ggdist:student_t]{dstudent_t}}, \code{\link[ggdist:theme_ggdist]{facet_title_left_horizontal}}, \code{\link[ggdist:theme_ggdist]{facet_title_right_horizontal}}, \code{\link[ggdist:tidy-format-translators]{from_broom_names}}, \code{\link[ggdist:tidy-format-translators]{from_ggmcmc_names}}, \code{\link[ggdist]{geom_dots}}, \code{\link[ggdist]{geom_dotsinterval}}, \code{\link[ggdist]{geom_interval}}, \code{\link[ggdist]{geom_lineribbon}}, \code{\link[ggdist]{geom_pointinterval}}, \code{\link[ggdist]{geom_slab}}, \code{\link[ggdist]{geom_slabinterval}}, \code{\link[ggdist:ggdist-ggproto]{GeomDots}}, \code{\link[ggdist:ggdist-ggproto]{GeomDotsinterval}}, \code{\link[ggdist:ggdist-ggproto]{GeomInterval}}, \code{\link[ggdist:ggdist-ggproto]{GeomLineribbon}}, \code{\link[ggdist:ggdist-ggproto]{GeomPointinterval}}, \code{\link[ggdist:ggdist-ggproto]{GeomSlab}}, \code{\link[ggdist:ggdist-ggproto]{GeomSlabinterval}}, \code{\link[ggdist:sub-geometry-scales]{guide_colorbar2}}, \code{\link[ggdist:sub-geometry-scales]{guide_colourbar2}}, \code{\link[ggdist:point_interval]{hdci}}, \code{\link[ggdist:point_interval]{hdi}}, \code{\link[ggdist]{marginalize_lkjcorr}}, \code{\link[ggdist:point_interval]{mean_hdci}}, \code{\link[ggdist:point_interval]{mean_hdi}}, \code{\link[ggdist:point_interval]{mean_qi}}, \code{\link[ggdist:point_interval]{median_hdci}}, \code{\link[ggdist:point_interval]{median_hdi}}, \code{\link[ggdist:point_interval]{median_qi}}, \code{\link[ggdist:point_interval]{Mode}}, \code{\link[ggdist:point_interval]{mode_hdci}}, \code{\link[ggdist:point_interval]{mode_hdi}}, \code{\link[ggdist:point_interval]{mode_qi}}, \code{\link[ggdist]{parse_dist}}, \code{\link[ggdist:lkjcorr_marginal]{plkjcorr_marginal}}, \code{\link[ggdist]{point_interval}}, \code{\link[ggdist:student_t]{pstudent_t}}, \code{\link[ggdist:point_interval]{qi}}, \code{\link[ggdist:lkjcorr_marginal]{qlkjcorr_marginal}}, \code{\link[ggdist:student_t]{qstudent_t}}, \code{\link[ggdist:parse_dist]{r_dist_name}}, \code{\link[ggdist:lkjcorr_marginal]{rlkjcorr_marginal}}, \code{\link[ggdist:student_t]{rstudent_t}}, \code{\link[ggdist:sub-geometry-scales]{scale_interval_alpha_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_interval_alpha_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_interval_color_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_interval_color_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_interval_colour_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_interval_colour_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_interval_linetype_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_interval_linetype_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_interval_size_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_interval_size_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_point_alpha_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_point_alpha_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_point_color_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_point_color_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_point_colour_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_point_colour_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_point_fill_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_point_fill_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_point_size_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_point_size_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_alpha_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_alpha_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_color_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_color_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_colour_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_colour_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_fill_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_fill_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_linetype_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_linetype_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_shape_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_shape_discrete}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_size_continuous}}, \code{\link[ggdist:sub-geometry-scales]{scale_slab_size_discrete}}, \code{\link[ggdist]{stat_ccdfinterval}}, \code{\link[ggdist]{stat_cdfinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_ccdfinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_cdfinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_dots}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_dotsinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_eye}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_gradientinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_halfeye}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_interval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_lineribbon}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_pointinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_slab}}, \code{\link[ggdist:ggdist-deprecated]{stat_dist_slabinterval}}, \code{\link[ggdist]{stat_dots}}, \code{\link[ggdist]{stat_dotsinterval}}, \code{\link[ggdist]{stat_eye}}, \code{\link[ggdist]{stat_gradientinterval}}, \code{\link[ggdist]{stat_halfeye}}, \code{\link[ggdist]{stat_histinterval}}, \code{\link[ggdist]{stat_interval}}, \code{\link[ggdist]{stat_lineribbon}}, \code{\link[ggdist]{stat_pointinterval}}, \code{\link[ggdist:ggdist-deprecated]{stat_sample_slabinterval}}, \code{\link[ggdist]{stat_slab}}, \code{\link[ggdist]{stat_slabinterval}}, \code{\link[ggdist:ggdist-deprecated]{StatDistSlabinterval}}, \code{\link[ggdist:ggdist-ggproto]{StatInterval}}, \code{\link[ggdist:ggdist-ggproto]{StatPointinterval}}, \code{\link[ggdist:ggdist-deprecated]{StatSampleSlabinterval}}, \code{\link[ggdist:ggdist-ggproto]{StatSlabinterval}}, \code{\link[ggdist]{theme_ggdist}}, \code{\link[ggdist:theme_ggdist]{theme_tidybayes}}, \code{\link[ggdist:tidy-format-translators]{to_broom_names}}, \code{\link[ggdist:tidy-format-translators]{to_ggmcmc_names}}}
 
   \item{posterior}{\code{\link[posterior:draws_summary]{summarise_draws}}}
 }}
diff --git a/man/spread_draws.Rd b/man/spread_draws.Rd
index 693b0063..584e38f3 100755
--- a/man/spread_draws.Rd
+++ b/man/spread_draws.Rd
@@ -12,6 +12,7 @@ gather_draws(
   sep = "[, ]",
   ndraws = NULL,
   seed = NULL,
+  draw_indices = c(".chain", ".iteration", ".draw"),
   n
 )
 
@@ -22,6 +23,7 @@ spread_draws(
   sep = "[, ]",
   ndraws = NULL,
   seed = NULL,
+  draw_indices = c(".chain", ".iteration", ".draw"),
   n
 )
 }
@@ -41,6 +43,12 @@ regular expression and number of dimensions are included in the output. Default
 
 \item{seed}{A seed to use when subsampling draws (i.e. when \code{ndraws} is not \code{NULL}).}
 
+\item{draw_indices}{Character vector of column names that should be treated
+as indices of draws. Operations are done within combinations of these values.
+The default is \code{c(".chain", ".iteration", ".draw")}, which is the same names
+used for chain, iteration, and draw indices returned by \code{\link[=tidy_draws]{tidy_draws()}}.
+Names in \code{draw_indices} that are not found in the data are ignored.}
+
 \item{n}{(Deprecated). Use \code{ndraws}.}
 }
 \value{
diff --git a/man/tidybayes-package.Rd b/man/tidybayes-package.Rd
index a7b5e3c7..517d6190 100644
--- a/man/tidybayes-package.Rd
+++ b/man/tidybayes-package.Rd
@@ -32,3 +32,21 @@ For a list of supported models, see \link{tidybayes-models}.
 Wickham, Hadley. (2014). Tidy data. \emph{Journal of Statistical Software},
 59(10), 1-23. \doi{10.18637/jss.v059.i10}.
 }
+\seealso{
+Useful links:
+\itemize{
+  \item \url{https://mjskay.github.io/tidybayes/}
+  \item \url{https://github.com/mjskay/tidybayes/}
+  \item Report bugs at \url{https://github.com/mjskay/tidybayes/issues/new}
+}
+
+}
+\author{
+\strong{Maintainer}: Matthew Kay \email{mjskay@northwestern.edu}
+
+Other contributors:
+\itemize{
+  \item Timothy Mastny \email{tim.mastny@gmail.com} [contributor]
+}
+
+}
diff --git a/man/unspread_draws.Rd b/man/unspread_draws.Rd
index edb7a970..5a4e8cd0 100755
--- a/man/unspread_draws.Rd
+++ b/man/unspread_draws.Rd
@@ -31,10 +31,11 @@ unspread_draws(
 
 \item{value}{The name of the column in \code{data} that contains draws from the variables.}
 
-\item{draw_indices}{Character vector of column names in \code{data} that
-should be treated as indices of draws. The default is \code{c(".chain",".iteration",".draw")},
-which are the same names used for chain, iteration, and draw indices returned by
-\code{\link[=spread_draws]{spread_draws()}} or \code{\link[=gather_draws]{gather_draws()}}.}
+\item{draw_indices}{Character vector of column names that should be treated
+as indices of draws. Operations are done within combinations of these values.
+The default is \code{c(".chain", ".iteration", ".draw")}, which is the same names
+used for chain, iteration, and draw indices returned by \code{\link[=tidy_draws]{tidy_draws()}}.
+Names in \code{draw_indices} that are not found in the data are ignored.}
 
 \item{drop_indices}{Drop the columns specified by \code{draw_indices} from the resulting data frame. Default \code{FALSE}.}
 }
diff --git a/tests/testthat/test.gather_draws.R b/tests/testthat/test.gather_draws.R
index bc186b6b..d5100d76 100755
--- a/tests/testthat/test.gather_draws.R
+++ b/tests/testthat/test.gather_draws.R
@@ -7,8 +7,6 @@ library(dplyr)
 library(tidyr)
 
 
-
-
 test_that("regular expressions for parameter names work on non-indexed parameters", {
   data(RankCorr, package = "ggdist")
 
@@ -42,3 +40,31 @@ test_that("gather_draws works on a combination of 0 and 1-dimensional values (wi
   expect_equivalent(result, ref)
   expect_equal(group_vars(result), group_vars(ref))
 })
+
+test_that("draw_indices works", {
+  df = data.frame(
+    .chain = rep(1:4, each = 4),
+    .iteration = rep(1:4, 4),
+    .draw = 1:16,
+    .warmup = rep(c(TRUE, TRUE, FALSE, FALSE), 4),
+    `x[1]` = 2:17,
+    `x[2]` = 3:18,
+    check.names = FALSE
+  )
+
+  ref = tibble(
+    i = rep(1:2, each = 16),
+    .chain = rep(1:4, each = 4, times = 2),
+    .iteration = rep(1:4, 8),
+    .draw = rep(1:16, 2),
+    .warmup = rep(c(TRUE, TRUE, FALSE, FALSE), 8),
+    .variable = "x",
+    .value = c(2:17, 3:18)
+  ) %>%
+    group_by(i, .variable)
+
+  result = gather_draws(df, x[i], draw_indices = c(".chain", ".iteration", ".draw", ".warmup"))
+
+  expect_equivalent(result, ref)
+  expect_equal(group_vars(result), group_vars(ref))
+})
diff --git a/tests/testthat/test.spread_draws.R b/tests/testthat/test.spread_draws.R
index 280b0d75..df608665 100755
--- a/tests/testthat/test.spread_draws.R
+++ b/tests/testthat/test.spread_draws.R
@@ -335,6 +335,33 @@ test_that("variable names containing regex special chars work", {
   expect_equal(spread_draws(RankCorr_t, `(Intercept)`), ref)
 })
 
+test_that("draw_indices works", {
+  df = data.frame(
+    .chain = rep(1:4, each = 4),
+    .iteration = rep(1:4, 4),
+    .draw = 1:16,
+    .warmup = rep(c(TRUE, TRUE, FALSE, FALSE), 4),
+    `x[1]` = 2:17,
+    `x[2]` = 3:18,
+    check.names = FALSE
+  )
+
+  ref = tibble(
+    i = rep(1:2, each = 16),
+    x = c(2:17, 3:18),
+    .chain = rep(1:4, each = 4, times = 2),
+    .iteration = rep(1:4, 8),
+    .draw = rep(1:16, 2),
+    .warmup = rep(c(TRUE, TRUE, FALSE, FALSE), 8)
+  ) %>%
+    group_by(i)
+
+  result = spread_draws(df, x[i], draw_indices = c(".chain", ".iteration", ".draw", ".warmup"))
+
+  expect_equivalent(result, ref)
+  expect_equal(group_vars(result), group_vars(ref))
+})
+
 
 # tests for nested syntax -------------------------------------------------