diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 495b80a3427..fce02bcb7bf 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -219,7 +219,7 @@ Calcite follows [Conventional Commits](https://www.conventionalcommits.org/en/v1
 Contributions should adhere to the `<type>(<scope>): <descriptive summary>` format and include the following:
 
 - [Commit type](#commit-type)
-- [Scope of change](#scope-of-change), _optional_
+- [Scope of change](#scope-of-change), *optional*
 - [Descriptive commit subject](#descriptive-commit-subject)
 
 Check out the [contribution example](#contribution-example) for a formatted example, and explore [breaking change formatting](#breaking-changes) for consideration during Calcite's breaking change releases.
@@ -240,7 +240,7 @@ Contributions must adhere to **one** of the following types:
 
 ### Scope of change
 
-_Optional_. Most contributions will include a scope, such as a component, multiple components, test(s), or utilities. For example:
+*Optional*. Most contributions will include a scope, such as a component, multiple components, test(s), or utilities. For example:
 
 - `text-area`
 - `dropdown, dropdown-group, dropdown-item`
diff --git a/packages/calcite-components/src/components/tree-item/tree-item.tsx b/packages/calcite-components/src/components/tree-item/tree-item.tsx
index 5977b27eecb..3dd14f10874 100644
--- a/packages/calcite-components/src/components/tree-item/tree-item.tsx
+++ b/packages/calcite-components/src/components/tree-item/tree-item.tsx
@@ -14,6 +14,7 @@ import {
   InteractiveContainer,
   updateHostInteraction,
 } from "../../utils/interactive";
+import { onToggleOpenCloseComponent, OpenCloseComponent } from "../../utils/openCloseComponent";
 import { CSS_UTILITY } from "../../utils/resources";
 import { FlipContext, Scale, SelectionMode } from "../interfaces";
 import { getIconScale } from "../../utils/component";
@@ -34,7 +35,7 @@ declare global {
  * @slot children - A slot for adding nested `calcite-tree` elements.
  * @slot actions-end - A slot for adding actions to the end of the component. It is recommended to use two or fewer actions.
  */
-export class TreeItem extends LitElement implements InteractiveComponent {
+export class TreeItem extends LitElement implements InteractiveComponent, OpenCloseComponent {
   // #region Static Members
 
   static override styles = styles;
@@ -53,6 +54,10 @@ export class TreeItem extends LitElement implements InteractiveComponent {
 
   private userChangedValue = false;
 
+  transitionProp = "opacity";
+
+  transitionEl: HTMLDivElement;
+
   // #endregion
 
   // #region State Properties
@@ -121,6 +126,18 @@ export class TreeItem extends LitElement implements InteractiveComponent {
   /** @private */
   calciteInternalTreeItemSelect = createEvent<TreeItemSelectDetail>({ cancelable: false });
 
+  /** Fires when the component is requested to be collapsed and before the closing transition begins. */
+  calciteTreeItemBeforeCollapsed = createEvent({ cancelable: false });
+
+  /** Fires when the component is added to the DOM but not rendered, and before the opening transition begins. */
+  calciteTreeItemBeforeExpanded = createEvent({ cancelable: false });
+
+  /** Fires when the component is collapsed and animation is complete. */
+  calciteTreeItemCollapsed = createEvent({ cancelable: false });
+
+  /** Fires when the component is expanded and animation is complete. */
+  calciteTreeItemExpanded = createEvent({ cancelable: false });
+
   // #endregion
 
   // #region Lifecycle
@@ -137,6 +154,7 @@ export class TreeItem extends LitElement implements InteractiveComponent {
 
   load(): void {
     requestAnimationFrame(() => (this.updateAfterInitialRender = true));
+    onToggleOpenCloseComponent(this);
   }
 
   override willUpdate(changes: PropertyValues<this>): void {
@@ -147,6 +165,7 @@ export class TreeItem extends LitElement implements InteractiveComponent {
     Docs: https://qawebgis.esri.com/arcgis-components/?path=/docs/lumina-transition-from-stencil--docs#watching-for-property-changes */
     if (changes.has("expanded") && (this.hasUpdated || this.expanded !== false)) {
       this.updateChildTree();
+      onToggleOpenCloseComponent(this);
     }
 
     if (changes.has("selected") && (this.hasUpdated || this.selected !== false)) {
@@ -208,6 +227,7 @@ export class TreeItem extends LitElement implements InteractiveComponent {
   private iconClickHandler(event: MouseEvent): void {
     event.stopPropagation();
     this.expanded = !this.expanded;
+    onToggleOpenCloseComponent(this);
   }
 
   private childrenClickHandler(event: MouseEvent): void {
@@ -230,6 +250,8 @@ export class TreeItem extends LitElement implements InteractiveComponent {
         break;
       case "Enter": {
         // activates a node, i.e., performs its default action. For parent nodes, one possible default action is to open or close the node. In single-select trees where selection does not follow focus (see note below), the default action is typically to select the focused node.
+        onToggleOpenCloseComponent(this);
+
         const link = Array.from(this.el.children).find((el) =>
           el.matches("a"),
         ) as HTMLAnchorElement;
@@ -245,6 +267,7 @@ export class TreeItem extends LitElement implements InteractiveComponent {
             updateItem: true,
           });
         }
+
         event.preventDefault();
       }
     }
@@ -340,6 +363,26 @@ export class TreeItem extends LitElement implements InteractiveComponent {
     }
   }
 
+  private setTransitionEl(el: HTMLDivElement): void {
+    this.transitionEl = el;
+  }
+
+  onBeforeExpanded(): void {
+    this.calciteTreeItemBeforeExpanded.emit();
+  }
+
+  onExpanded(): void {
+    this.calciteTreeItemExpanded.emit();
+  }
+
+  onBeforeCollapsed(): void {
+    this.calciteTreeItemBeforeCollapsed.emit();
+  }
+
+  onCollapsed(): void {
+    this.calciteTreeItemCollapsed.emit();
+  }
+
   // #endregion
 
   // #region Rendering
@@ -483,6 +526,7 @@ export class TreeItem extends LitElement implements InteractiveComponent {
             }}
             data-test-id="calcite-tree-children"
             onClick={this.childrenClickHandler}
+            ref={this.setTransitionEl}
             role={this.hasChildren ? "group" : undefined}
           >
             <slot name={SLOTS.children} onSlotChange={this.handleChildrenSlotChange} />
diff --git a/packages/calcite-components/src/demos/tree.html b/packages/calcite-components/src/demos/tree.html
index ba5fb9b300b..32464b5fb3b 100644
--- a/packages/calcite-components/src/demos/tree.html
+++ b/packages/calcite-components/src/demos/tree.html
@@ -51,7 +51,7 @@ <h1 style="margin: 0 auto; text-align: center">Tree</h1>
             <calcite-tree-item>
               Child 2
 
-              <calcite-tree slot="children">
+              <calcite-tree slot="children" id="tree-item">
                 <calcite-tree-item> Grandchild 1 </calcite-tree-item>
 
                 <calcite-tree-item> Grandchild 2 </calcite-tree-item>
@@ -67,6 +67,29 @@ <h1 style="margin: 0 auto; text-align: center">Tree</h1>
               </calcite-tree>
             </calcite-tree-item>
           </calcite-tree>
+          <script>
+            const treeItem = document.getElementById("tree-item");
+
+            window.onload = () => {
+              if (treeItem) {
+                treeItem.addEventListener("calciteTreeItemBeforeCollapsed", () => {
+                  console.log("calciteTreeItemBeforeCollapsed event fired");
+                });
+
+                treeItem.addEventListener("calciteTreeItemBeforeExpanded", () => {
+                  console.log("calciteTreeItemBeforeExpanded event fired");
+                });
+
+                treeItem.addEventListener("calciteTreeItemCollapsed", () => {
+                  console.log("calciteTreeItemCollapsed event fired");
+                });
+
+                treeItem.addEventListener("calciteTreeItemExpanded", () => {
+                  console.log("calciteTreeItemExpanded event fired");
+                });
+              }
+            };
+          </script>
         </div>
 
         <div class="child">
diff --git a/packages/calcite-components/src/utils/openCloseComponent.ts b/packages/calcite-components/src/utils/openCloseComponent.ts
index 64a65bec863..5c73b8747c2 100644
--- a/packages/calcite-components/src/utils/openCloseComponent.ts
+++ b/packages/calcite-components/src/utils/openCloseComponent.ts
@@ -10,6 +10,15 @@ export interface OpenCloseComponent {
   /** The host element. */
   readonly el: HTMLElement;
 
+  /** When true, the component closes. */
+  closed?: boolean;
+
+  /** When true, the component collapses. */
+  collapsed?: boolean;
+
+  /** When true, the component is expanded. */
+  expanded?: boolean;
+
   /**
    * Specifies property on which active transition is watched for.
    *
@@ -24,16 +33,28 @@ export interface OpenCloseComponent {
   transitionEl: HTMLElement;
 
   /** Defines method for `beforeOpen` event handler. */
-  onBeforeOpen: () => void;
+  onBeforeOpen?: () => void;
 
   /** Defines method for `open` event handler: */
-  onOpen: () => void;
+  onOpen?: () => void;
 
   /** Defines method for `beforeClose` event handler: */
-  onBeforeClose: () => void;
+  onBeforeClose?: () => void;
 
   /** Defines method for `close` event handler: */
-  onClose: () => void;
+  onClose?: () => void;
+
+  /** Defines method for `beforeExpanded` event handler. */
+  onBeforeExpanded?: () => void;
+
+  /** Defines method for `expanded` event handler: */
+  onExpanded?: () => void;
+
+  /** Defines method for `beforeCollapsed` event handler: */
+  onBeforeCollapsed?: () => void;
+
+  /** Defines method for `collapsed` event handler: */
+  onCollapsed?: () => void;
 }
 
 function isOpen(component: OpenCloseComponent): boolean {
@@ -56,7 +77,7 @@ function isOpen(component: OpenCloseComponent): boolean {
  * async toggleModal(value: boolean): Promise<void> {
  *    onToggleOpenCloseComponent(this);
  * }
- * @param component - OpenCloseComponent uses `open` prop to emit (before)open/close.
+ * @param component - OpenCloseComponent uses `open`/`close` or `expanded`/`collapsed` props to emit (before)open/close or (before)expanded/collapsed respectively.
  */
 export function onToggleOpenCloseComponent(component: OpenCloseComponent): void {
   requestAnimationFrame((): void => {