diff --git a/google/cloud/bigquery/_helpers.py b/google/cloud/bigquery/_helpers.py
index 88a0944c48f3..222cf2579c17 100644
--- a/google/cloud/bigquery/_helpers.py
+++ b/google/cloud/bigquery/_helpers.py
@@ -54,9 +54,9 @@ def _record_from_json(value, field):
         for subfield, cell in zip(field.fields, value['f']):
             converter = _CELLDATA_FROM_JSON[subfield.field_type]
             if field.mode == 'REPEATED':
-                value = [converter(item, field) for item in cell['v']]
+                value = [converter(item, subfield) for item in cell['v']]
             else:
-                value = converter(cell['v'], field)
+                value = converter(cell['v'], subfield)
             record[subfield.name] = value
         return record
 
diff --git a/unit_tests/bigquery/test__helpers.py b/unit_tests/bigquery/test__helpers.py
index 6521a6338b23..8e885c31cd59 100644
--- a/unit_tests/bigquery/test__helpers.py
+++ b/unit_tests/bigquery/test__helpers.py
@@ -15,6 +15,255 @@
 import unittest
 
 
+class Test_not_null(unittest.TestCase):
+
+    def _callFUT(self, value, field):
+        from google.cloud.bigquery._helpers import _not_null
+        return _not_null(value, field)
+
+    def test_w_none_nullable(self):
+        self.assertFalse(self._callFUT(None, _Field('NULLABLE')))
+
+    def test_w_none_required(self):
+        self.assertTrue(self._callFUT(None, _Field('REQUIRED')))
+
+    def test_w_value(self):
+        self.assertTrue(self._callFUT(object(), object()))
+
+
+class Test_int_from_json(unittest.TestCase):
+
+    def _callFUT(self, value, field):
+        from google.cloud.bigquery._helpers import _int_from_json
+        return _int_from_json(value, field)
+
+    def test_w_none_nullable(self):
+        self.assertIsNone(self._callFUT(None, _Field('NULLABLE')))
+
+    def test_w_none_required(self):
+        with self.assertRaises(TypeError):
+            self._callFUT(None, _Field('REQUIRED'))
+
+    def test_w_string_value(self):
+        coerced = self._callFUT('42', object())
+        self.assertEqual(coerced, 42)
+
+    def test_w_float_value(self):
+        coerced = self._callFUT(42, object())
+        self.assertEqual(coerced, 42)
+
+
+class Test_float_from_json(unittest.TestCase):
+
+    def _callFUT(self, value, field):
+        from google.cloud.bigquery._helpers import _float_from_json
+        return _float_from_json(value, field)
+
+    def test_w_none_nullable(self):
+        self.assertIsNone(self._callFUT(None, _Field('NULLABLE')))
+
+    def test_w_none_required(self):
+        with self.assertRaises(TypeError):
+            self._callFUT(None, _Field('REQUIRED'))
+
+    def test_w_string_value(self):
+        coerced = self._callFUT('3.1415', object())
+        self.assertEqual(coerced, 3.1415)
+
+    def test_w_float_value(self):
+        coerced = self._callFUT(3.1415, object())
+        self.assertEqual(coerced, 3.1415)
+
+
+class Test_bool_from_json(unittest.TestCase):
+
+    def _callFUT(self, value, field):
+        from google.cloud.bigquery._helpers import _bool_from_json
+        return _bool_from_json(value, field)
+
+    def test_w_none_nullable(self):
+        self.assertIsNone(self._callFUT(None, _Field('NULLABLE')))
+
+    def test_w_none_required(self):
+        with self.assertRaises(AttributeError):
+            self._callFUT(None, _Field('REQUIRED'))
+
+    def test_w_value_t(self):
+        coerced = self._callFUT('T', object())
+        self.assertTrue(coerced)
+
+    def test_w_value_true(self):
+        coerced = self._callFUT('True', object())
+        self.assertTrue(coerced)
+
+    def test_w_value_1(self):
+        coerced = self._callFUT('1', object())
+        self.assertTrue(coerced)
+
+    def test_w_value_other(self):
+        coerced = self._callFUT('f', object())
+        self.assertFalse(coerced)
+
+
+class Test_datetime_from_json(unittest.TestCase):
+
+    def _callFUT(self, value, field):
+        from google.cloud.bigquery._helpers import _datetime_from_json
+        return _datetime_from_json(value, field)
+
+    def test_w_none_nullable(self):
+        self.assertIsNone(self._callFUT(None, _Field('NULLABLE')))
+
+    def test_w_none_required(self):
+        with self.assertRaises(TypeError):
+            self._callFUT(None, _Field('REQUIRED'))
+
+    def test_w_string_value(self):
+        import datetime
+        from google.cloud._helpers import _EPOCH
+        coerced = self._callFUT('1.234567', object())
+        self.assertEqual(
+            coerced,
+            _EPOCH + datetime.timedelta(seconds=1, microseconds=234567))
+
+    def test_w_float_value(self):
+        import datetime
+        from google.cloud._helpers import _EPOCH
+        coerced = self._callFUT(1.234567, object())
+        self.assertEqual(
+            coerced,
+            _EPOCH + datetime.timedelta(seconds=1, microseconds=234567))
+
+
+class Test_record_from_json(unittest.TestCase):
+
+    def _callFUT(self, value, field):
+        from google.cloud.bigquery._helpers import _record_from_json
+        return _record_from_json(value, field)
+
+    def test_w_none_nullable(self):
+        self.assertIsNone(self._callFUT(None, _Field('NULLABLE')))
+
+    def test_w_none_required(self):
+        with self.assertRaises(TypeError):
+            self._callFUT(None, _Field('REQUIRED'))
+
+    def test_w_nullable_subfield_none(self):
+        subfield = _Field('NULLABLE', 'age', 'INTEGER')
+        field = _Field('REQUIRED', fields=[subfield])
+        value = {'f': [{'v': None}]}
+        coerced = self._callFUT(value, field)
+        self.assertEqual(coerced, {'age': None})
+
+    def test_w_scalar_subfield(self):
+        subfield = _Field('REQUIRED', 'age', 'INTEGER')
+        field = _Field('REQUIRED', fields=[subfield])
+        value = {'f': [{'v': 42}]}
+        coerced = self._callFUT(value, field)
+        self.assertEqual(coerced, {'age': 42})
+
+    def test_w_repeated_subfield(self):
+        subfield = _Field('REPEATED', 'color', 'STRING')
+        field = _Field('REQUIRED', fields=[subfield])
+        value = {'f': [{'v': ['red', 'yellow', 'blue']}]}
+        coerced = self._callFUT(value, field)
+        self.assertEqual(coerced, {'color': ['red', 'yellow', 'blue']})
+
+    def test_w_record_subfield(self):
+        full_name = _Field('REQUIRED', 'full_name', 'STRING')
+        area_code = _Field('REQUIRED', 'area_code', 'STRING')
+        local_number = _Field('REQUIRED', 'local_number', 'STRING')
+        rank = _Field('REQUIRED', 'rank', 'INTEGER')
+        phone = _Field('NULLABLE', 'phone', 'RECORD',
+                       fields=[area_code, local_number, rank])
+        person = _Field('REQUIRED', 'person', 'RECORD',
+                        fields=[full_name, phone])
+        value = {
+            'f': [
+                {'v': 'Phred Phlyntstone'},
+                {'v': {'f': [{'v': '800'}, {'v': '555-1212'}, {'v': 1}]}},
+            ],
+        }
+        expected = {
+            'full_name': 'Phred Phlyntstone',
+            'phone': {
+                'area_code': '800',
+                'local_number': '555-1212',
+                'rank': 1,
+            }
+        }
+        coerced = self._callFUT(value, person)
+        self.assertEqual(coerced, expected)
+
+
+class Test_string_from_json(unittest.TestCase):
+
+    def _callFUT(self, value, field):
+        from google.cloud.bigquery._helpers import _string_from_json
+        return _string_from_json(value, field)
+
+    def test_w_none_nullable(self):
+        self.assertIsNone(self._callFUT(None, _Field('NULLABLE')))
+
+    def test_w_none_required(self):
+        self.assertIsNone(self._callFUT(None, _Field('RECORD')))
+
+    def test_w_string_value(self):
+        coerced = self._callFUT('Wonderful!', object())
+        self.assertEqual(coerced, 'Wonderful!')
+
+
+class Test_rows_from_json(unittest.TestCase):
+
+    def _callFUT(self, value, field):
+        from google.cloud.bigquery._helpers import _rows_from_json
+        return _rows_from_json(value, field)
+
+    def test_w_record_subfield(self):
+        full_name = _Field('REQUIRED', 'full_name', 'STRING')
+        area_code = _Field('REQUIRED', 'area_code', 'STRING')
+        local_number = _Field('REQUIRED', 'local_number', 'STRING')
+        rank = _Field('REQUIRED', 'rank', 'INTEGER')
+        phone = _Field('NULLABLE', 'phone', 'RECORD',
+                       fields=[area_code, local_number, rank])
+        color = _Field('REPEATED', 'color', 'STRING')
+        schema = [full_name, phone, color]
+        rows = [
+            {'f': [
+                {'v': 'Phred Phlyntstone'},
+                {'v': {'f': [{'v': '800'}, {'v': '555-1212'}, {'v': 1}]}},
+                {'v': ['orange', 'black']},
+            ]},
+            {'f': [
+                {'v': 'Bharney Rhubble'},
+                {'v': {'f': [{'v': '877'}, {'v': '768-5309'}, {'v': 2}]}},
+                {'v': ['brown']},
+            ]},
+            {'f': [
+                {'v': 'Wylma Phlyntstone'},
+                {'v': None},
+                {'v': []},
+            ]},
+        ]
+        phred_phone = {
+            'area_code': '800',
+            'local_number': '555-1212',
+            'rank': 1,
+        }
+        bharney_phone = {
+            'area_code': '877',
+            'local_number': '768-5309',
+            'rank': 2,
+        }
+        expected = [
+            ('Phred Phlyntstone', phred_phone, ['orange', 'black']),
+            ('Bharney Rhubble', bharney_phone, ['brown']),
+            ('Wylma Phlyntstone', None, []),
+        ]
+        coerced = self._callFUT(rows, schema)
+        self.assertEqual(coerced, expected)
+
+
 class Test_ConfigurationProperty(unittest.TestCase):
 
     def _getTargetClass(self):
@@ -114,3 +363,12 @@ def __init__(self):
         del wrapper.attr
         self.assertEqual(wrapper.attr, None)
         self.assertEqual(wrapper._configuration._attr, None)
+
+
+class _Field(object):
+
+    def __init__(self, mode, name='unknown', field_type='UNKNOWN', fields=()):
+        self.mode = mode
+        self.name = name
+        self.field_type = field_type
+        self.fields = fields