diff --git a/src/ops/sources/google_drive.rs b/src/ops/sources/google_drive.rs
index 937509cd..8befd7b0 100644
--- a/src/ops/sources/google_drive.rs
+++ b/src/ops/sources/google_drive.rs
@@ -9,10 +9,13 @@ use google_drive3::{
 use http_body_util::BodyExt;
 use hyper_rustls::HttpsConnector;
 use hyper_util::client::legacy::connect::HttpConnector;
+use indexmap::IndexSet;
 use log::debug;
 
 use crate::ops::sdk::*;
 
+const FOLDER_MIME_TYPE: &'static str = "application/vnd.google-apps.folder";
+
 #[derive(Debug, Deserialize)]
 pub struct Spec {
     service_account_credential_path: String,
@@ -28,7 +31,6 @@ struct Executor {
 
 impl Executor {
     async fn new(spec: Spec) -> Result<Self> {
-        // let user_secret = read_authorized_user_secret(spec.service_account_credential_path).await?;
         let service_account_key =
             read_service_account_key(spec.service_account_credential_path).await?;
         let auth = ServiceAccountAuthenticator::builder(service_account_key)
@@ -64,12 +66,18 @@ fn escape_string(s: &str) -> String {
     escaped
 }
 
-#[async_trait]
-impl SourceExecutor for Executor {
-    async fn list_keys(&self) -> Result<Vec<KeyValue>> {
-        let query = format!("'{}' in parents", escape_string(&self.root_folder_id));
+impl Executor {
+    async fn traverse_folder(
+        &self,
+        folder_id: &str,
+        visited_folder_ids: &mut IndexSet<String>,
+        result: &mut IndexSet<KeyValue>,
+    ) -> Result<()> {
+        if !visited_folder_ids.insert(folder_id.to_string()) {
+            return Ok(());
+        }
+        let query = format!("'{}' in parents", escape_string(folder_id));
         let mut next_page_token: Option<String> = None;
-        let mut result = Vec::new();
         loop {
             let mut list_call = self
                 .drive_hub
@@ -83,9 +91,12 @@ impl SourceExecutor for Executor {
             let (_, files) = list_call.doit().await?;
             if let Some(files) = files.files {
                 for file in files {
-                    debug!("file: {:?}", file);
                     if let Some(id) = file.id {
-                        result.push(KeyValue::Str(Arc::from(id)));
+                        if file.mime_type.as_ref() == Some(&FOLDER_MIME_TYPE.to_string()) {
+                            Box::pin(self.traverse_folder(&id, visited_folder_ids, result)).await?;
+                        } else {
+                            result.insert(KeyValue::Str(Arc::from(id)));
+                        }
                     }
                 }
             }
@@ -94,7 +105,17 @@ impl SourceExecutor for Executor {
                 break;
             }
         }
-        Ok(result)
+        Ok(())
+    }
+}
+
+#[async_trait]
+impl SourceExecutor for Executor {
+    async fn list_keys(&self) -> Result<Vec<KeyValue>> {
+        let mut result = IndexSet::new();
+        self.traverse_folder(&self.root_folder_id, &mut IndexSet::new(), &mut result)
+            .await?;
+        Ok(result.into_iter().collect())
     }
 
     async fn get_value(&self, key: &KeyValue) -> Result<Option<FieldValues>> {