diff --git a/surveys/threads.md b/surveys/threads.md
new file mode 100644
index 0000000..d0cd5fb
--- /dev/null
+++ b/surveys/threads.md
@@ -0,0 +1,44 @@
+# Threads
+
+Using _OS threads_, also known as _native threads_, there is exactly
+one operating system thread for each virtual machine thread.
+
+Using _virtual threads_, also known as _green threads_ (after the
+_Green Team_ working on Java at Sun), each OS thread can switch
+between multiple VM threads using co-operative multitasking. The
+threads visible to the Scheme program are the VM threads; the OS
+threads are an internal implementation detail.
+
+|Scheme|Standard API|Custom API|OS threads|Virtual threads|Re-entrant interpreter
+|------|------------|----------|----------|---------------|----------------------
+|Bigloo|SRFI 18|?|["POSIX threads"][bigloo-pthread]|["Fair threads"][bigloo-fthread]|?
+|Chez Scheme|?|?|?|?|?
+|Chibi-Scheme|?|?|?|?|?
+|CHICKEN|SRFI 18|?|Yes|No|?|?|?
+|Cyclone|SRFI 18*|?|No|pthreads|?|?|?
+|Gambit|SRFI 18|?|Yes|No|?|?|?
+|Gauche|SRFI 18|?|No|pthreads, Win32|?|?|?
+|Gerbil|?|?|?|?|?
+|Guile|SRFI 18|[Here][guile-custom]|[pthreads][guile-pthreads]|[`(ice-9 futures)`][guile-futures]|Yes
+|IronScheme|?|?|?|?|?
+|Kawa|?|?|?|?|?
+|Larceny|?|?|?|?|?
+|Loko|?|?|?|?|?
+|MIT Scheme|?|?|?|?|?
+|Racket|?|?|?|?|?
+|Sagittarius|?|?|?|?|?
+|Scheme48|?|?|?|?|?
+|STKlos|SRFI 18|?|No|pthreads|Yes
+|TinyScheme|No|?|?|?|?|Yes
+|Unsyntax|?|?|?|?|?
+|Vicare|?|?|?|?|?
+|Ypsilon|?|?|Yes|?|?
+
+*) Partial support
+
+[bigloo-fthread]: https://www-sop.inria.fr/mimosa/fp/Bigloo/manual-chapter16.html#Fair%20Threads
+[bigloo-pthread]: [https://www-sop.inria.fr/mimosa/fp/Bigloo/manual-chapter16.html#Posix%20Threads]
+
+[guile-pthreads]: https://www.gnu.org/software/guile/manual/html_node/Scheduling.html
+[guile-custom]: https://www.gnu.org/software/guile/manual/html_node/Threads.html
+[guile-futures]: https://www.gnu.org/software/guile/manual/html_node/Futures.html
diff --git a/www-index.scm b/www-index.scm
index 8cbd079..4ecdf37 100644
--- a/www-index.scm
+++ b/www-index.scm
@@ -8,7 +8,8 @@
   "minischeme-history"
   "optionality"
   "scheme-on-windows"
-  "standalone-executables")
+  "standalone-executables"
+  "threads")
 
  ("Macros"
   "macroexpand"