diff --git a/.changeset/fix-legacy-maxEntityDepth.md b/.changeset/fix-legacy-maxEntityDepth.md
new file mode 100644
index 000000000000..b5e0a621887a
--- /dev/null
+++ b/.changeset/fix-legacy-maxEntityDepth.md
@@ -0,0 +1,10 @@
+---
+'@data-client/endpoint': patch
+'@data-client/rest': patch
+'@data-client/graphql': patch
+---
+
+Fix `maxEntityDepth` missing from Entity types on TypeScript 4.0
+
+`maxEntityDepth` was not included in the TS 4.0 legacy type definitions,
+so TypeScript 4.0 users could not set or reference this property on Entity classes.
diff --git a/packages/endpoint/src-4.0-types/schemas/EntityTypes.d.ts b/packages/endpoint/src-4.0-types/schemas/EntityTypes.d.ts
index 14e05e0f6506..f5e6cb83d627 100644
--- a/packages/endpoint/src-4.0-types/schemas/EntityTypes.d.ts
+++ b/packages/endpoint/src-4.0-types/schemas/EntityTypes.d.ts
@@ -30,6 +30,7 @@ export interface IEntityClass<TBase extends Constructor = any> {
      * @see https://dataclient.io/rest/api/Entity#indexes
      */
     indexes?: readonly string[] | undefined;
+    maxEntityDepth?: number | undefined;
     /**
      * A unique identifier for each Entity
      *