diff --git a/src/TreeViewList/TreeViewList.spec.tsx b/src/TreeViewList/TreeViewList.spec.tsx
index 49a42756..5f5b6288 100644
--- a/src/TreeViewList/TreeViewList.spec.tsx
+++ b/src/TreeViewList/TreeViewList.spec.tsx
@@ -142,7 +142,7 @@ test("should hide child when is collapsed", async ({ page }) => {
     if (frame !== null) {
       await page
         .frameLocator('iframe[title="storybook-preview-iframe"]')
-        .getByText("Aerodynamics")
+        .getByText("Aerodynamics", { exact: true })
         .click();
       await expect(
         page
@@ -151,7 +151,7 @@ test("should hide child when is collapsed", async ({ page }) => {
       ).toBeVisible();
       await page
         .frameLocator('iframe[title="storybook-preview-iframe"]')
-        .getByText("Aerodynamics")
+        .getByText("Aerodynamics", { exact: true })
         .click();
       await expect(
         page
@@ -168,7 +168,7 @@ test("should expand the parent and child nodes that match the search term", asyn
   page
 }) => {
   await page.goto(
-    "http://localhost:6006/?path=/story/lists-treeviewlist--default&args=enableSearch:true;expandSearchResults:true"
+    "http://localhost:6006/?path=/story/lists-treeviewlist--default&args=enableSearch:true;expandSearchResults:true;expandItems:2"
   );
 
   // Wait for the iframe to be attached in the DOM.
@@ -177,7 +177,7 @@ test("should expand the parent and child nodes that match the search term", asyn
   await page
     .frameLocator('iframe[title="storybook-preview-iframe"]')
     .getByPlaceholder("Search")
-    .fill("rear");
+    .fill("front");
 
   // Get the Frame object for the iframe.
   const frameElement = await page.$('iframe[title="storybook-preview-iframe"]');
@@ -193,7 +193,7 @@ test("should expand the parent and child nodes that match the search term", asyn
 
       const elementCount = liElements.length;
 
-      expect(elementCount).toBe(5);
+      expect(elementCount).toBe(2);
     } else {
       throw new Error("Frame object is null");
     }
diff --git a/src/TreeViewList/TreeViewList.stories.tsx b/src/TreeViewList/TreeViewList.stories.tsx
index 1180faef..3625ad2b 100644
--- a/src/TreeViewList/TreeViewList.stories.tsx
+++ b/src/TreeViewList/TreeViewList.stories.tsx
@@ -23,6 +23,7 @@ const Template: StoryFn<TreeViewListProps> = args => {
 export const Default = {
   args: {
     enableSearch: false,
+    expandItems: 1,
     expandSearchResults: false,
     items,
     selected: "",
@@ -35,6 +36,7 @@ export const Default = {
 export const WithSearch = {
   args: {
     enableSearch: true,
+    expandItems: 1,
     expandSearchResults: true,
     items,
     selected: "",
@@ -47,6 +49,7 @@ export const WithSearch = {
 export const CustomWidth = {
   args: {
     enableSearch: true,
+    expandItems: 1,
     expandSearchResults: true,
     items,
     selected: "",
diff --git a/src/TreeViewList/TreeViewList.tsx b/src/TreeViewList/TreeViewList.tsx
index dcf60571..3b6446d3 100644
--- a/src/TreeViewList/TreeViewList.tsx
+++ b/src/TreeViewList/TreeViewList.tsx
@@ -1,4 +1,4 @@
-import { Box, Tooltip } from "@mui/material";
+import { Box, Tooltip, debounce } from "@mui/material";
 import React, { useEffect, useState } from "react";
 import { TreeItem, TreeView } from "@mui/x-tree-view";
 import { TreeNodeItem, TreeViewListProps } from "./TreeViewList.types";
@@ -13,6 +13,7 @@ import SearchBar from "../SearchBar/SearchBar";
  * @param props - The properties for the tree view list.
  * @property props.enableSearch - If true, the search input is displayed. Defaults to false.
  * @property props.expandSearchResults - If true, the tree nodes will be automatically expanded when a search term is entered. Defaults to false.
+ * @property props.expandItems - The number of items to expand
  * @property props.items - The items to display in the tree view list.
  * @property props.onNodeSelect - The function to call when a node is selected.
  * @property props.onNodeToggle - The function to call when a node is toggled.
@@ -23,6 +24,7 @@ import SearchBar from "../SearchBar/SearchBar";
 const TreeViewList = ({
   enableSearch = false,
   expandSearchResults = false,
+  expandItems = 1,
   items,
   onNodeSelect,
   onNodeToggle,
@@ -37,7 +39,13 @@ const TreeViewList = ({
   const [searchValue, setSearchValue] = useState("");
 
   // state for expanded nodes
-  const [defaultExpanded, setDefaultExpanded] = useState<string[]>([]);
+  const [expandedNodes, setExpandedNodes] = useState<string[]>([]);
+
+  // state for user expanded nodes
+  const [userExpanded, setUserExpanded] = useState<string[]>([]);
+
+  // state for the node we are hovered over
+  const [hoveredNode, setHoveredNode] = useState<string>("");
 
   // update tree display items when the items prop changes or when the search input changes
   useEffect(() => {
@@ -57,33 +65,81 @@ const TreeViewList = ({
     }
   }, [enableSearch, items, searchValue]);
 
-  // if search is enabled and expandSearchResults is true, expand all nodes when the tree display items change
-  useEffect(() => {
-    if (enableSearch && expandSearchResults && searchValue !== "") {
-      const expandedNodes: string[] = [];
-      const expandAllNodes = (items: TreeNodeItem[]) => {
+  // count the number of last children in the tree
+  const countLastChild = (items: TreeNodeItem[]) => {
+    let count = 0;
+
+    for (const item of items) {
+      // Check if the object has a 'children' property and it's not empty
+      if (item.children && item.children.length > 0) {
+        // If the object has children, recursively call the function on its children
+        count += countLastChild(item.children);
+      } else {
+        // If the object has no children, it is a last child
+        count += 1;
+      }
+    }
+
+    return count;
+  };
+
+  // expand the nodes when the search input changes
+  const expandNodes = () => {
+    let searchedNodes: string[] = [];
+    const expandChildNodes = (items: TreeNodeItem[]) => {
+      // If the condition is not met for the entire items array, return early
+      if (countLastChild(items) > expandItems) {
+        // reset the searched nodes array
+        searchedNodes = [];
+        return;
+      }
+
+      // if the number of last children is less than or equal to the expandItems, expand the nodes
+      if (countLastChild(items) <= expandItems) {
         for (const item of items) {
-          expandedNodes.push(item.nodeId);
+          // if the node has children, expand it and call the function on its children
           if (item.children) {
-            expandAllNodes(item.children);
+            searchedNodes.push(item.nodeId);
+            expandChildNodes(item.children);
           }
         }
-      };
-      expandAllNodes(treeDisplayItems);
-      setDefaultExpanded(expandedNodes);
+      }
+    };
+    expandChildNodes(treeDisplayItems);
+    // update the expanded nodes with the searched nodes
+    setExpandedNodes(prevState => [...prevState, ...searchedNodes]);
+  };
+
+  // debounce the expandNodes function to prevent it from being called too frequently
+  const debouncedExpandAllNodes = debounce(expandNodes, 100);
+
+  // if search is enabled and expandSearchResults is true, expand the nodes when the tree display items change
+  useEffect(() => {
+    if (enableSearch && expandSearchResults && searchValue !== "") {
+      debouncedExpandAllNodes();
     } else {
-      setDefaultExpanded([]);
+      // if enableSearch is false and expandSearchResults is false and searchValue is empty, update the expanded nodes with the user expanded nodes
+      setExpandedNodes(userExpanded);
     }
-  }, [enableSearch, expandSearchResults, searchValue, treeDisplayItems]);
+  }, [
+    userExpanded,
+    debouncedExpandAllNodes,
+    expandedNodes,
+    enableSearch,
+    expandSearchResults,
+    searchValue
+  ]);
 
   // render the tree nodes with optional tooltips
   const renderTree = (nodes: TreeNodeItem[]) =>
     nodes.map(node => (
       <TooltipTreeItem
         disabled={node.disabled}
+        hoveredNode={hoveredNode}
         key={node.nodeId}
         label={node.label}
         nodeId={node.nodeId}
+        setHoveredNode={setHoveredNode}
         tooltip={node.tooltip}
       >
         {Array.isArray(node.children) && node.children.length > 0
@@ -101,13 +157,23 @@ const TreeViewList = ({
         />
       ) : null}
       <TreeView
-        key={`${searchValue} + ${defaultExpanded.length}`} // key to force re-render so that we can reset the expanded nodes when the search input changes but still allow user to expand/collapse nodes
         defaultCollapseIcon={<RemoveIcon />}
         defaultExpandIcon={<AddIcon />}
-        defaultExpanded={defaultExpanded}
+        expanded={expandedNodes}
         selected={selected}
-        onNodeSelect={onNodeSelect}
-        onNodeToggle={onNodeToggle}
+        onNodeSelect={(event, nodeId) => {
+          const node = getNodeById(treeDisplayItems, nodeId);
+          const isChild = Boolean(
+            node && (!node.children || node.children.length === 0)
+          );
+          if (onNodeSelect) {
+            const nodeDetails = { isChild };
+            onNodeSelect(event, nodeId, nodeDetails);
+          }
+        }}
+        onNodeToggle={(event, nodeId) => {
+          setUserExpanded([...nodeId]);
+        }}
       >
         {renderTree(treeDisplayItems)}
       </TreeView>
@@ -115,6 +181,30 @@ const TreeViewList = ({
   );
 };
 
+/**
+ * Recursively finds a node by its ID.
+ *
+ * @param nodes - The nodes to search.
+ * @param nodeId - The ID of the node to find.
+ * @returns The node with the specified ID, or null if not found.
+ */
+const getNodeById = (
+  nodes: TreeNodeItem[],
+  nodeId: string
+): TreeNodeItem | null => {
+  for (const node of nodes) {
+    if (node.nodeId === nodeId) {
+      return node;
+    } else if (node.children) {
+      const result = getNodeById(node.children, nodeId);
+      if (result) {
+        return result;
+      }
+    }
+  }
+  return null;
+};
+
 /**
  * Creates a tree view list item with an optional tooltip.
  *
@@ -128,20 +218,34 @@ const TreeViewList = ({
 const TooltipTreeItem = (
   props: Pick<TreeNodeItem, "disabled" | "label" | "nodeId" | "tooltip"> & {
     children?: React.ReactNode;
+    hoveredNode: string;
+    setHoveredNode: (nodeId: string) => void;
   }
 ) => {
+  // destructure the hoveredNode and setHoveredNode from the props and pass the rest of the props to the TreeItem
+  const { hoveredNode, setHoveredNode, ...rest } = props;
+
   return (
     <Tooltip
-      disableFocusListener
       title={props.tooltip ? <>{props.tooltip}</> : ""}
-      placement="right"
+      placement="right-start"
+      open={props.hoveredNode === props.nodeId}
+      disableFocusListener
     >
       <TreeItem
-        {...props}
+        {...rest}
         sx={theme => ({
           color: theme.palette.text.primary,
           padding: "5px"
         })}
+        onMouseOver={event => {
+          event.stopPropagation();
+          setHoveredNode(props.nodeId);
+        }}
+        onMouseOut={event => {
+          event.stopPropagation();
+          setHoveredNode("");
+        }}
       />
     </Tooltip>
   );
diff --git a/src/TreeViewList/TreeViewList.types.ts b/src/TreeViewList/TreeViewList.types.ts
index 9cddc8f8..c995aaf8 100644
--- a/src/TreeViewList/TreeViewList.types.ts
+++ b/src/TreeViewList/TreeViewList.types.ts
@@ -30,6 +30,17 @@ export type TreeNodeItem = {
   tooltip?: string;
 };
 
+/**
+ * Callback fired when a node is selected.
+ */
+type OnNodeSelect = (
+  event: React.SyntheticEvent,
+  nodeId: string,
+  nodeDetails: {
+    isChild: boolean;
+  }
+) => void;
+
 /**
  * Properties for the TreeViewList component.
  */
@@ -44,6 +55,11 @@ export type TreeViewListProps = {
    */
   expandSearchResults?: boolean;
 
+  /**
+   * The number of items to automactically expand when expandSearchResults is true. Defaults to 1.
+   */
+  expandItems?: number;
+
   /**
    * The items to display in the tree view list.
    */
@@ -52,7 +68,7 @@ export type TreeViewListProps = {
   /**
    * Callback fired when tree items are selected/unselected.
    */
-  onNodeSelect: TreeViewProps<false>["onNodeSelect"];
+  onNodeSelect: OnNodeSelect;
 
   /**
    * Callback fired when tree items are expanded/collapsed.
diff --git a/src/TreeViewList/example-items.json b/src/TreeViewList/example-items.json
index 878914e3..fa1eb083 100644
--- a/src/TreeViewList/example-items.json
+++ b/src/TreeViewList/example-items.json
@@ -2,6 +2,7 @@
   {
     "label": "Aerodynamics",
     "nodeId": "AER",
+    "tooltip": "Aerodynamics description goes here",
     "children": [
       {
         "label": "Drag Coefficient",