diff --git a/src/pynwb/base.py b/src/pynwb/base.py
index 8b4daf48f..e2e4038c0 100644
--- a/src/pynwb/base.py
+++ b/src/pynwb/base.py
@@ -72,6 +72,46 @@ def get_data_interface(self, **kwargs):
         warn(PendingDeprecationWarning('get_data_interface will be replaced by get'))
         return self.get(kwargs['data_interface_name'])
 
+    def __len__(self):
+        """Get the number of data interfaces in this ProcessingModule.
+
+        Returns
+        -------
+        int
+            Number of data interfaces
+        """
+        return len(self.data_interfaces)
+
+    def keys(self):
+        """Get the names of data interfaces in this ProcessingModule.
+
+        Returns
+        -------
+        KeysView
+            View of interface names
+        """
+        return self.data_interfaces.keys()
+
+    def values(self):
+        """Get the data interfaces in this ProcessingModule.
+
+        Returns
+        -------
+        ValuesView
+            View of interfaces
+        """
+        return self.data_interfaces.values()
+
+    def items(self):
+        """Get the (name, interface) pairs in this ProcessingModule.
+
+        Returns
+        -------
+        ItemsView
+            View of (name, interface) pairs
+        """
+        return self.data_interfaces.items()
+
 
 @register_class('TimeSeries', CORE_NAMESPACE)
 class TimeSeries(NWBDataInterface):
diff --git a/tests/unit/test_base.py b/tests/unit/test_base.py
index 5af4986ac..623219af7 100644
--- a/tests/unit/test_base.py
+++ b/tests/unit/test_base.py
@@ -94,6 +94,35 @@ def test_getitem(self):
         tmp = self.pm["test_ts"]
         self.assertIs(tmp, ts)
 
+    def test_len(self):
+        """Test that len() returns number of data interfaces."""
+        self.assertEqual(len(self.pm), 0)
+        ts = self._create_time_series()
+        self.pm.add(ts)
+        self.assertEqual(len(self.pm), 1)
+        ts2 = TimeSeries(name="test_ts2", data=[1, 2, 3], unit="unit", rate=1.0)
+        self.pm.add(ts2)
+        self.assertEqual(len(self.pm), 2)
+
+    def test_dict_methods(self):
+        """Test dictionary-like methods (keys, values, items)."""
+        ts = self._create_time_series()
+        ts2 = TimeSeries(name="test_ts2", data=[1, 2, 3], unit="unit", rate=1.0)
+        self.pm.add(ts)
+        self.pm.add(ts2)
+
+        # Test keys()
+        keys = self.pm.keys()
+        self.assertEqual(set(keys), {"test_ts", "test_ts2"})
+
+        # Test values()
+        values = self.pm.values()
+        self.assertEqual(set(values), {ts, ts2})
+
+        # Test items()
+        items = self.pm.items()
+        self.assertEqual(set(items), {("test_ts", ts), ("test_ts2", ts2)})
+
 
 class TestTimeSeries(TestCase):
     def test_init_no_parent(self):