diff --git a/.changeset/tasty-timers-change.md b/.changeset/tasty-timers-change.md
new file mode 100644
index 0000000000..ade1ffbcf5
--- /dev/null
+++ b/.changeset/tasty-timers-change.md
@@ -0,0 +1,6 @@
+---
+'@twilio-paste/side-modal': patch
+'@twilio-paste/core': patch
+---
+
+[Side Modal] set screen position to fixed to ensure the dialog is always full height in long scrolling screens'
diff --git a/packages/paste-core/components/side-modal/src/SideModalContainer.tsx b/packages/paste-core/components/side-modal/src/SideModalContainer.tsx
index f96f2f576f..057a4e7951 100644
--- a/packages/paste-core/components/side-modal/src/SideModalContainer.tsx
+++ b/packages/paste-core/components/side-modal/src/SideModalContainer.tsx
@@ -27,6 +27,7 @@ const BaseSideModalContainer: React.FC<React.PropsWithChildren<SideModalContaine
     state ||
     useNonModalDialogPrimitiveState({
       modal: true,
+      unstable_fixed: true,
       ...initialState,
     });