diff --git a/tests/providers/test_provider.py b/tests/providers/test_provider.py
index 80aadd6..0d64dbc 100644
--- a/tests/providers/test_provider.py
+++ b/tests/providers/test_provider.py
@@ -16,3 +16,28 @@ def test_setProvider(disconnected_provider):
     web3.setProvider(None)
     assert web3.currentProvider is None
     assert web3._requestManager.provider is None
+
+
+def test_isConnected(web3):
+    """
+    Web3.isConnected() returns True when connected to a node.
+    """
+    assert web3.isConnected() is True
+
+
+def test_isConnected_no_provider():
+    """
+    Web3.isConnected() returns False when not configured with a provider.
+    """
+    web3 = Web3(None)
+    assert web3.isConnected() is False
+
+
+def test_isConnected_disconnected(disconnected_provider):
+    """
+    Web3.isConnected() returns False when configured with a provider
+    that's not connected to a node.
+    """
+    web3 = Web3(disconnected_provider)
+    assert web3.isConnected() is False
+
diff --git a/web3/main.py b/web3/main.py
index de5f319..8d876bf 100644
--- a/web3/main.py
+++ b/web3/main.py
@@ -98,7 +98,7 @@ class Web3(object):
         return self._requestManager.request_blocking('web3_sha3', [hex_string])
 
     def isConnected(self):
-        return self.currentProvider and self.currentProvider.isConnected()
+        return self.currentProvider is not None and self.currentProvider.isConnected()
 
     def createBatch(self):
         raise NotImplementedError("Not Implemented")
diff --git a/web3/web3/provider.py b/web3/web3/provider.py
index 9d11b66..1e316bf 100644
--- a/web3/web3/provider.py
+++ b/web3/web3/provider.py
@@ -6,7 +6,7 @@ import itertools
 from web3.utils.encoding import (
     force_bytes,
     force_obj_to_text,
-)
+    force_text)
 
 
 class BaseProvider(object):
@@ -23,3 +23,15 @@ class BaseProvider(object):
             "params": params or [],
             "id": next(self.request_counter),
         })))
+
+    def isConnected(self):
+        try:
+            response_raw = self.make_request('web3_clientVersion', [])
+            response = json.loads(force_text(response_raw))
+        except IOError:
+            return False
+        else:
+            assert response['jsonrpc'] == '2.0'
+            assert 'error' not in response
+            return True
+        assert False