diff --git a/packages/react-resizable-panels-website/root.css b/packages/react-resizable-panels-website/root.css
index bd7e38c0c..1e7039153 100644
--- a/packages/react-resizable-panels-website/root.css
+++ b/packages/react-resizable-panels-website/root.css
@@ -35,13 +35,6 @@ code {
   border-radius: 0.25em;
 }
 
-hr {
-  width: 100%;
-  height: 1px;
-  border: none;
-  background-color: #454950;
-}
-
 h2 {
   font-weight: normal;
   margin: 0.5rem 0;
diff --git a/packages/react-resizable-panels-website/src/HorizontalGroup.tsx b/packages/react-resizable-panels-website/src/HorizontalGroup.tsx
index 5e37c5f45..e57481808 100644
--- a/packages/react-resizable-panels-website/src/HorizontalGroup.tsx
+++ b/packages/react-resizable-panels-website/src/HorizontalGroup.tsx
@@ -72,7 +72,7 @@ export default function HorizontalGroup({
               reset vertical sizes
               <div className={styles.VerticalDot} />
             </button>
-            <hr />
+            <span className={styles.HorizontalDivider} />
             <button
               className={styles.Button}
               onClick={() => clearSavedSizes(GROUP_ID, GROUP_ID_VERTICAL)}
diff --git a/packages/react-resizable-panels-website/src/VerticalGroup.tsx b/packages/react-resizable-panels-website/src/VerticalGroup.tsx
index bfa5f2341..d3f2fbff1 100644
--- a/packages/react-resizable-panels-website/src/VerticalGroup.tsx
+++ b/packages/react-resizable-panels-website/src/VerticalGroup.tsx
@@ -7,72 +7,101 @@ import styles from "./styles.module.css";
 export const GROUP_ID = "vertical";
 
 export function VerticalGroup() {
-  const [isPanelHidden, setIsPanelHidden] = useState(false);
-
-  const hidePanel = () => setIsPanelHidden(true);
-  const showPanel = () => setIsPanelHidden(false);
+  const [showTopPanel, setShowTopPanel] = useState(true);
+  const [showBottomPanel, setShowBottomPanel] = useState(true);
 
   return (
-    <PanelGroup autoSaveId={GROUP_ID} direction="vertical">
-      <Panel
-        className={styles.PanelRow}
-        defaultSize={0.35}
-        id="top"
-        minSize={0.25}
-      >
-        <div
-          className={
-            isPanelHidden ? styles.VerticalFiller : styles.VerticalFillerTop
-          }
-          style={{ backgroundColor: "var(--color-vertical)" }}
-        >
-          <p className={styles.ParagraphOfText}>
-            This is a "<em>vertical</em>" <code>PanelGroup</code>.
-          </p>
-          <p className={styles.ParagraphOfText}>
-            It has a solid resize bar, similar to Chrome devtools or VS Code.
-          </p>
-          <p className={styles.ParagraphOfText}>
-            It uses the <code>minSize</code> prop to prevent it from shrinking
-            to less than 35% of the total height.
-          </p>
-
-          {isPanelHidden && (
-            <button
-              className={styles.ButtonBottom}
-              onClick={showPanel}
-              id="blah"
-            >
-              Show panel
-            </button>
-          )}
-        </div>
-      </Panel>
-      {isPanelHidden || (
+    <div
+      className={styles.VerticalFiller}
+      style={{ backgroundColor: "var(--color-vertical)" }}
+    >
+      <PanelGroup autoSaveId={GROUP_ID} direction="vertical">
+        {showTopPanel && (
+          <Panel
+            className={styles.PanelColumn}
+            defaultSize={0.35}
+            id="top"
+            minSize={0.2}
+            order={1}
+          >
+            <div className={styles.VerticalFiller}>
+              <p className={styles.ParagraphOfText}>
+                This is a "<em>vertical</em>" <code>PanelGroup</code>.
+              </p>
+              <p className={styles.ParagraphOfText}>
+                <button
+                  className={styles.Button}
+                  onClick={() => setShowTopPanel(false)}
+                >
+                  Hide panel
+                </button>
+              </p>
+            </div>
+            <PanelResizeHandle panelBefore="top" panelAfter="middle">
+              <div className={styles.VerticalResizeBar} />
+            </PanelResizeHandle>
+          </Panel>
+        )}
         <Panel
           className={styles.PanelColumn}
-          defaultSize={0.65}
-          id="bottom"
+          defaultSize={0.35}
+          id="middle"
           minSize={0.35}
+          order={2}
         >
-          <PanelResizeHandle panelBefore="top" panelAfter="bottom">
-            <div className={styles.VerticalResizeBar} />
-          </PanelResizeHandle>
-          <div
-            className={styles.VerticalFillerBottom}
-            style={{ backgroundColor: "var(--color-vertical)" }}
-          >
+          <div className={styles.VerticalFiller}>
             <p className={styles.ParagraphOfText}>
-              This panel's visibility can be toggled on or off.
+              This panel uses the <code>minSize</code> prop to prevent it from
+              shrinking to less than 35% of the total height.
             </p>
-            <p className={styles.ParagraphOfText}>
-              <button className={styles.Button} onClick={hidePanel}>
-                Hide panel
+
+            {!showTopPanel && (
+              <button
+                className={styles.ButtonTop}
+                onClick={() => setShowTopPanel(true)}
+              >
+                Show top panel
               </button>
-            </p>
+            )}
+
+            {!showBottomPanel && (
+              <button
+                className={styles.ButtonBottom}
+                onClick={() => setShowBottomPanel(true)}
+              >
+                Show bottom panel
+              </button>
+            )}
           </div>
         </Panel>
-      )}
-    </PanelGroup>
+        {showBottomPanel && (
+          <Panel
+            className={styles.PanelColumn}
+            defaultSize={0.65}
+            id="bottom"
+            minSize={0.2}
+            order={3}
+          >
+            <PanelResizeHandle panelBefore="middle" panelAfter="bottom">
+              <div className={styles.VerticalResizeBar} />
+            </PanelResizeHandle>
+            <div className={styles.VerticalFiller}>
+              <p className={styles.ParagraphOfText}>
+                This group uses a solid resize bar, similar to Chrome devtools
+                or VS Code.
+              </p>
+              <p className={styles.ParagraphOfText}>
+                <button
+                  className={styles.Button}
+                  onClick={() => setShowBottomPanel(false)}
+                >
+                  Hide panel
+                </button>
+              </p>
+            </div>
+          </Panel>
+        )}
+      </PanelGroup>
+    </div>
   );
 }
diff --git a/packages/react-resizable-panels-website/src/styles.module.css b/packages/react-resizable-panels-website/src/styles.module.css
index ebf8f68e6..dd5e9a1e0 100644
--- a/packages/react-resizable-panels-website/src/styles.module.css
+++ b/packages/react-resizable-panels-website/src/styles.module.css
@@ -15,12 +15,9 @@
 .HorizontalFiller,
 .HorizontalFillerLeft,
 .HorizontalFillerRight,
-.VerticalFiller,
-.VerticalFillerBottom,
-.VerticalFillerTop {
+.VerticalFiller {
   height: 100%;
   width: 100%;
-  background-color: #192230;
   display: flex;
   flex-direction: column;
   align-items: center;
@@ -31,14 +28,6 @@
 .VerticalFiller {
   border-radius: 0.5rem;
 }
-.VerticalFillerTop {
-  border-top-left-radius: 0.5rem;
-  border-top-right-radius: 0.5rem;
-}
-.VerticalFillerBottom {
-  border-bottom-left-radius: 0.5rem;
-  border-bottom-right-radius: 0.5rem;
-}
 
 .PanelRow {
   display: flex;
@@ -62,7 +51,8 @@
 }
 
 .Button,
-.ButtonBottom {
+.ButtonBottom,
+.ButtonTop {
   color: #ffffff;
   background: #2a3343;
   border: 1px solid #18181a;
@@ -71,7 +61,8 @@
   cursor: pointer;
 }
 .Button:hover,
-.ButtonBottom:hover {
+.ButtonBottom:hover,
+.ButtonTop:hover {
   background: #454950;
 }
 
@@ -101,3 +92,17 @@
   bottom: 1ch;
   right: 1ch;
 }
+.ButtonTop {
+  position: absolute;
+  top: 1ch;
+  right: 1ch;
+}
+
+.HorizontalDivider {
+  display: block;
+  width: 100%;
+  height: 1px;
+  border: none;
+  background-color: #454950;
+  margin: 0.5rem 0;
+}
diff --git a/packages/react-resizable-panels/CHANGELOG.md b/packages/react-resizable-panels/CHANGELOG.md
index 36dc47938..1afa7b552 100644
--- a/packages/react-resizable-panels/CHANGELOG.md
+++ b/packages/react-resizable-panels/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## 0.0.4
+* [#8](https://github.com/bvaughn/react-resizable-panels/issues/8): Added optional `order` prop to `Panel` to improve conditional rendering.
+
 ## 0.0.3
 * [#3](https://github.com/bvaughn/react-resizable-panels/issues/3): `Panel`s can be conditionally rendered within a group. `PanelGroup` will persist separate layouts for each combination of visible panels.
 
diff --git a/packages/react-resizable-panels/README.md b/packages/react-resizable-panels/README.md
index 28f45788f..745887f4f 100644
--- a/packages/react-resizable-panels/README.md
+++ b/packages/react-resizable-panels/README.md
@@ -39,6 +39,7 @@ import { Panel, PanelGroup, PanelResizeHandle } from "react-resizable-panels";
 | `defaultSize` | `?number`   | Initial size of panel (relative to other panels within the group)
 | `id`          | `string`    | Panel id (must be unique within the current group)
 | `minSize`     | `?number`   | Minum allowable size of panel (0.0 - 1.0)
+| `order`       | `?number`   | Order of panel within group; required for groups with conditionally rendered panels
 
 ### `PanelResizeHandle`
 | prop          | type         | description
diff --git a/packages/react-resizable-panels/src/Panel.tsx b/packages/react-resizable-panels/src/Panel.tsx
index 0c29f09c4..d23492892 100644
--- a/packages/react-resizable-panels/src/Panel.tsx
+++ b/packages/react-resizable-panels/src/Panel.tsx
@@ -11,12 +11,14 @@ export default function Panel({
   defaultSize = 0.1,
   id,
   minSize = 0.1,
+  order = null,
 }: {
   children?: ReactNode;
   className?: string;
   defaultSize?: number;
   id: string;
   minSize?: number;
+  order?: number | null;
 }) {
   const context = useContext(PanelGroupContext);
   if (context === null) {
@@ -40,6 +42,7 @@ export default function Panel({
       defaultSize,
       id,
       minSize,
+      order,
     };
 
     registerPanel(id, panel);
@@ -47,7 +50,7 @@ export default function Panel({
     return () => {
       unregisterPanel(id);
     };
-  }, [defaultSize, id, minSize, registerPanel, unregisterPanel]);
+  }, [defaultSize, id, minSize, order, registerPanel, unregisterPanel]);
 
   const style = getPanelStyle(id);
 
diff --git a/packages/react-resizable-panels/src/PanelGroup.tsx b/packages/react-resizable-panels/src/PanelGroup.tsx
index 5a80d1dff..998e4f13e 100644
--- a/packages/react-resizable-panels/src/PanelGroup.tsx
+++ b/packages/react-resizable-panels/src/PanelGroup.tsx
@@ -91,7 +91,7 @@ export default function PanelGroup({
     if (defaultSizes != null) {
       setSizes(defaultSizes);
     } else {
-      const panelsArray: PanelData[] = Array.from(panels.values());
+      const panelsArray = panelsMapToSortedArray(panels);
       const totalWeight = panelsArray.reduce((weight, panel) => {
         return weight + panel.defaultSize;
       }, 0);
@@ -237,7 +237,7 @@ function adjustByDelta(
     return prevSizes;
   }
 
-  const panelsArray: PanelData[] = Array.from(panels.values());
+  const panelsArray = panelsMapToSortedArray(panels);
 
   const nextSizes = prevSizes.concat();
 
@@ -295,7 +295,8 @@ function createLocalStorageKey(
   autoSaveId: string,
   panels: Map<string, PanelData>
 ): string {
-  const panelIds = Array.from(panels.keys()).sort();
+  const panelsArray = panelsMapToSortedArray(panels);
+  const panelIds = panelsArray.map((panel) => panel.id);
 
   return `PanelGroup:sizes:${autoSaveId}${panelIds.join("|")}`;
 }
@@ -308,7 +309,7 @@ function getOffset(
   height: number,
   width: number
 ): number {
-  const panelsArray: PanelData[] = Array.from(panels.values());
+  const panelsArray = panelsMapToSortedArray(panels);
 
   let index = panelsArray.findIndex((panel) => panel.id === id);
   if (index < 0) {
@@ -339,7 +340,7 @@ function getSize(
     return totalSize;
   }
 
-  const panelsArray: PanelData[] = Array.from(panels.values());
+  const panelsArray = panelsMapToSortedArray(panels);
 
   const index = panelsArray.findIndex((panel) => panel.id === id);
   const size = sizes[index];
@@ -349,3 +350,7 @@ function getSize(
 
   return Math.round(size * totalSize);
 }
+
+function panelsMapToSortedArray(panels: Map<string, PanelData>): PanelData[] {
+  return Array.from(panels.values()).sort((a, b) => a.order - b.order);
+}
diff --git a/packages/react-resizable-panels/src/types.ts b/packages/react-resizable-panels/src/types.ts
index ff5744d8b..0f5d2e689 100644
--- a/packages/react-resizable-panels/src/types.ts
+++ b/packages/react-resizable-panels/src/types.ts
@@ -4,6 +4,7 @@ export type PanelData = {
   defaultSize: number;
   id: string;
   minSize: number;
+  order: number | null;
 };
 
 export type ResizeHandler = (event: MouseEvent) => void;