diff --git a/google/api_core/universe_domain.py b/google/api_core/universe_domain.py
new file mode 100644
index 000000000..5ee35f0a8
--- /dev/null
+++ b/google/api_core/universe_domain.py
@@ -0,0 +1,9 @@
+
+GOOGLE_DEFAULT_UNIVERSE = "googleapis.com"
+
+def _validate_universe_domain(client_universe, credentials_universe):
+    """Validates the universe domain used by the client instance against
+        the universe domain in the credentials.
+    """
+    if client_universe != credentials_universe:
+        raise ValueError(f"The configured universe domain ({client_universe}) does not match the universe domain found in the credentials ({credentials_universe}). If you haven't configured the universe domain explicitly, `googleapis.com` is the default.")
\ No newline at end of file