diff --git a/specification/cognitiveservices/data-plane/FormRecognizer/preview/v1.0/FormRecognizer.json b/specification/cognitiveservices/data-plane/FormRecognizer/preview/v1.0/FormRecognizer.json
index febeee2f6215..ae94b69a285d 100644
--- a/specification/cognitiveservices/data-plane/FormRecognizer/preview/v1.0/FormRecognizer.json
+++ b/specification/cognitiveservices/data-plane/FormRecognizer/preview/v1.0/FormRecognizer.json
@@ -69,6 +69,9 @@
         "x-ms-examples": {
           "Train new model example": {
             "$ref": "./examples/Train.json"
+          },
+          "Train new model example, subfolder filter options": {
+            "$ref": "./examples/TrainWithSubFolders.json"
           }
         }
       }
@@ -296,6 +299,26 @@
           "maxLength": 2048,
           "minLength": 0,
           "type": "string"
+        },
+        "sourceFilter":{
+          "$ref":"#/definitions/TrainSourceFilter",
+          "description":"Get or set filter to further search the\r\nsource path for content."
+        }
+      }
+    },
+    "TrainSourceFilter":{
+      "description":"Filters to be applied when traversing a data source.",
+      "type":"object",
+      "properties":{
+        "prefix":{
+          "description":"A case-sensitive prefix string to filter content\r\nunder the source location. For e.g., when using a Azure Blob\r\nUri use the prefix to restrict subfolders for content.",
+          "maxLength":128,
+          "minLength":0,
+          "type":"string"
+        },
+        "includeSubFolders":{
+          "description":"A flag to indicate if sub folders within the set of\r\nprefix folders will also need to be included when searching\r\nfor content to be preprocessed.",
+          "type":"boolean"
         }
       }
     },
diff --git a/specification/cognitiveservices/data-plane/FormRecognizer/preview/v1.0/examples/TrainWithSubFolders.json b/specification/cognitiveservices/data-plane/FormRecognizer/preview/v1.0/examples/TrainWithSubFolders.json
new file mode 100644
index 000000000000..40dc153c23aa
--- /dev/null
+++ b/specification/cognitiveservices/data-plane/FormRecognizer/preview/v1.0/examples/TrainWithSubFolders.json
@@ -0,0 +1,55 @@
+{
+  "parameters": {
+    "Endpoint": "{Endpoint}",
+    "Content-Type": "application/json",
+    "Ocp-Apim-Subscription-Key": "{API key}",
+    "body": {},
+    "trainRequest": {
+      "source": "/input/data",
+      "sourceFilter": {
+        "prefix": "",
+        "includeSubFolders": false
+      }
+    }
+  },
+  "responses": {
+    "200": {
+      "body": {
+        "modelId": "ad1901b6-ddaa-4249-8938-3f03f65cc893",
+        "trainingDocuments": [
+          {
+            "documentName": "0.pdf",
+            "pages": 1,
+            "errors": [],
+            "status": "success"
+          },
+          {
+            "documentName": "1.pdf",
+            "pages": 1,
+            "errors": [],
+            "status": "success"
+          },
+          {
+            "documentName": "2.pdf",
+            "pages": 1,
+            "errors": [],
+            "status": "success"
+          },
+          {
+            "documentName": "3.pdf",
+            "pages": 1,
+            "errors": [],
+            "status": "success"
+          },
+          {
+            "documentName": "4.pdf",
+            "pages": 1,
+            "errors": [],
+            "status": "success"
+          }
+        ],
+        "errors": []
+      }
+    }
+  }
+}