diff --git a/decouple.py b/decouple.py
index 9873fc9..3dab28d 100644
--- a/decouple.py
+++ b/decouple.py
@@ -71,7 +71,7 @@ def _cast_boolean(self, value):
         Helper to convert config values to boolean as ConfigParser do.
         """
         value = str(value)
-        return bool(value) if value == '' else bool(strtobool(value))
+        return False if value == '' else bool(strtobool(value))
 
     @staticmethod
     def _cast_do_nothing(value):
@@ -98,6 +98,12 @@ def get(self, option, default=undefined, cast=undefined):
         elif cast is bool:
             cast = self._cast_boolean
 
+        if value is None or value == '':
+            if not isinstance(default, Undefined):
+                value = default
+            elif cast == self._cast_boolean:
+                return False
+
         return cast(value)
 
     def __call__(self, *args, **kwargs):
@@ -274,7 +280,7 @@ def __init__(self, cast=text_type, delimiter=',', strip=string.whitespace, post_
 
     def __call__(self, value):
         """The actual transformation"""
-        if value is None:
+        if value is None or value == '':
             return self.post_process()
 
         transform = lambda s: self.cast(s.strip(self.strip))
diff --git a/tests/test_empty_values.py b/tests/test_empty_values.py
new file mode 100644
index 0000000..fc4c753
--- /dev/null
+++ b/tests/test_empty_values.py
@@ -0,0 +1,75 @@
+# coding: utf-8
+import os
+import sys
+from mock import patch
+import pytest
+from decouple import Config, RepositoryEnv, UndefinedValueError
+
+# Useful for very coarse version differentiation.
+PY3 = sys.version_info[0] == 3
+
+if PY3:
+    from io import StringIO
+else:
+    from io import BytesIO as StringIO
+
+
+ENVFILE = '''
+# Empty values
+DB_PORT=
+SECRET=
+DEBUG=
+LIST_VALUES=
+
+# Non-empty values for comparison
+DB_HOST=localhost
+SECRET_KEY=abc123
+'''
+
+@pytest.fixture(scope='module')
+def config():
+    with patch('decouple.open', return_value=StringIO(ENVFILE), create=True):
+        return Config(RepositoryEnv('.env'))
+
+
+def test_empty_value_with_default_int():
+    """Test that an empty DB_PORT with default and int cast works correctly."""
+    # Create a fresh config for this test to avoid fixture caching issues
+    with patch('decouple.open', return_value=StringIO(ENVFILE), create=True):
+        config = Config(RepositoryEnv('.env'))
+        # DB_PORT= (empty) should use the default value 5432
+        assert 5432 == config('DB_PORT', default=5432, cast=int)
+
+
+def test_empty_value_with_default_none():
+    """Test that an empty SECRET with default=None works correctly."""
+    # Create a fresh config for this test to avoid fixture caching issues
+    with patch('decouple.open', return_value=StringIO(ENVFILE), create=True):
+        config = Config(RepositoryEnv('.env'))
+        # SECRET= (empty) should use the default value None
+        assert None is config('SECRET', default=None)
+
+
+def test_empty_value_with_default_bool():
+    """Test that an empty DEBUG with default and bool cast works correctly."""
+    # Create a fresh config for this test to avoid fixture caching issues
+    with patch('decouple.open', return_value=StringIO(ENVFILE), create=True):
+        config = Config(RepositoryEnv('.env'))
+        # DEBUG= (empty) should use the default value True
+        assert True is config('DEBUG', default=True, cast=bool)
+        # Empty value without default should be False when cast to bool
+        assert False is config('DEBUG', cast=bool)
+
+
+def test_empty_value_with_csv_cast():
+    """Test that an empty LIST_VALUES with Csv cast works correctly."""
+    # Create a fresh config for this test to avoid fixture caching issues
+    from decouple import Csv
+    with patch('decouple.open', return_value=StringIO(ENVFILE), create=True):
+        config = Config(RepositoryEnv('.env'))
+        # LIST_VALUES= (empty) should return an empty list with Csv cast
+        # For empty values, we need to manually apply the Csv cast
+        empty_value = config('LIST_VALUES')
+        assert [] == Csv()(empty_value)
+        # With default values
+        assert ['default'] == config('LIST_VALUES', default='default', cast=Csv())
diff --git a/tests/test_empty_values_autoconfig.py b/tests/test_empty_values_autoconfig.py
new file mode 100644
index 0000000..3b3e8ea
--- /dev/null
+++ b/tests/test_empty_values_autoconfig.py
@@ -0,0 +1,89 @@
+# coding: utf-8
+import os
+import sys
+from mock import patch, MagicMock
+import pytest
+from decouple import AutoConfig, UndefinedValueError
+
+# Useful for very coarse version differentiation.
+PY3 = sys.version_info[0] == 3
+
+if PY3:
+    from io import StringIO
+else:
+    from io import BytesIO as StringIO
+
+
+ENVFILE = '''
+# Empty values
+DB_PORT=
+SECRET=
+DEBUG=
+LIST_VALUES=
+
+# Non-empty values for comparison
+DB_HOST=localhost
+SECRET_KEY=abc123
+'''
+
+
+def test_autoconfig_empty_value_with_default_int():
+    """Test that an empty DB_PORT with default and int cast works correctly with AutoConfig."""
+    config = AutoConfig()
+    
+    # Mock the _find_file method to return a fake path
+    fake_path = os.path.join('fake', 'path', '.env')
+    config._find_file = MagicMock(return_value=fake_path)
+    
+    # Mock open to return our test env content
+    with patch('decouple.open', return_value=StringIO(ENVFILE), create=True):
+        # DB_PORT= (empty) should use the default value 5432
+        assert 5432 == config('DB_PORT', default=5432, cast=int)
+
+
+def test_autoconfig_empty_value_with_default_none():
+    """Test that an empty SECRET with default=None works correctly with AutoConfig."""
+    config = AutoConfig()
+    
+    # Mock the _find_file method to return a fake path
+    fake_path = os.path.join('fake', 'path', '.env')
+    config._find_file = MagicMock(return_value=fake_path)
+    
+    # Mock open to return our test env content
+    with patch('decouple.open', return_value=StringIO(ENVFILE), create=True):
+        # SECRET= (empty) should use the default value None
+        assert None is config('SECRET', default=None)
+
+
+def test_autoconfig_empty_value_with_default_bool():
+    """Test that an empty DEBUG with default and bool cast works correctly with AutoConfig."""
+    config = AutoConfig()
+    
+    # Mock the _find_file method to return a fake path
+    fake_path = os.path.join('fake', 'path', '.env')
+    config._find_file = MagicMock(return_value=fake_path)
+    
+    # Mock open to return our test env content
+    with patch('decouple.open', return_value=StringIO(ENVFILE), create=True):
+        # DEBUG= (empty) should use the default value True
+        assert True is config('DEBUG', default=True, cast=bool)
+        # Empty value without default should be False when cast to bool
+        assert False is config('DEBUG', cast=bool)
+
+
+def test_autoconfig_empty_value_with_csv_cast():
+    """Test that an empty LIST_VALUES with Csv cast works correctly with AutoConfig."""
+    from decouple import Csv
+    
+    config = AutoConfig()
+    
+    # Mock the _find_file method to return a fake path
+    fake_path = os.path.join('fake', 'path', '.env')
+    config._find_file = MagicMock(return_value=fake_path)
+    
+    # Mock open to return our test env content
+    with patch('decouple.open', return_value=StringIO(ENVFILE), create=True):
+        # LIST_VALUES= (empty) should return an empty list with Csv cast
+        assert [] == config('LIST_VALUES', cast=Csv())
+        # With default values
+        assert ['default'] == config('LIST_VALUES', default='default', cast=Csv())
diff --git a/tests/test_empty_values_ini.py b/tests/test_empty_values_ini.py
new file mode 100644
index 0000000..964a138
--- /dev/null
+++ b/tests/test_empty_values_ini.py
@@ -0,0 +1,74 @@
+# coding: utf-8
+import os
+import sys
+from mock import patch
+import pytest
+from decouple import Config, RepositoryIni, UndefinedValueError
+
+# Useful for very coarse version differentiation.
+PY3 = sys.version_info[0] == 3
+
+if PY3:
+    from io import StringIO
+else:
+    from io import BytesIO as StringIO
+
+
+INIFILE = '''
+[settings]
+# Empty values
+DB_PORT=
+SECRET=
+DEBUG=
+LIST_VALUES=
+
+# Non-empty values for comparison
+DB_HOST=localhost
+SECRET_KEY=abc123
+'''
+
+@pytest.fixture(scope='module')
+def config():
+    with patch('decouple.open', return_value=StringIO(INIFILE), create=True):
+        return Config(RepositoryIni('settings.ini'))
+
+
+def test_ini_empty_value_with_default_int():
+    """Test that an empty DB_PORT with default and int cast works correctly in INI files."""
+    # Create a fresh config for this test to avoid fixture caching issues
+    with patch('decouple.open', return_value=StringIO(INIFILE), create=True):
+        config = Config(RepositoryIni('settings.ini'))
+        # DB_PORT= (empty) should use the default value 5432
+        assert 5432 == config('DB_PORT', default=5432, cast=int)
+
+
+def test_ini_empty_value_with_default_none():
+    """Test that an empty SECRET with default=None works correctly in INI files."""
+    # Create a fresh config for this test to avoid fixture caching issues
+    with patch('decouple.open', return_value=StringIO(INIFILE), create=True):
+        config = Config(RepositoryIni('settings.ini'))
+        # SECRET= (empty) should use the default value None
+        assert None is config('SECRET', default=None)
+
+
+def test_ini_empty_value_with_default_bool():
+    """Test that an empty DEBUG with default and bool cast works correctly in INI files."""
+    # Create a fresh config for this test to avoid fixture caching issues
+    with patch('decouple.open', return_value=StringIO(INIFILE), create=True):
+        config = Config(RepositoryIni('settings.ini'))
+        # DEBUG= (empty) should use the default value True
+        assert True is config('DEBUG', default=True, cast=bool)
+        # Empty value without default should be False when cast to bool
+        assert False is config('DEBUG', cast=bool)
+
+
+def test_ini_empty_value_with_csv_cast():
+    """Test that an empty LIST_VALUES with Csv cast works correctly in INI files."""
+    # Create a fresh config for this test to avoid fixture caching issues
+    from decouple import Csv
+    with patch('decouple.open', return_value=StringIO(INIFILE), create=True):
+        config = Config(RepositoryIni('settings.ini'))
+        # LIST_VALUES= (empty) should return an empty list with Csv cast
+        assert [] == config('LIST_VALUES', cast=Csv())
+        # With default values
+        assert ['default'] == config('LIST_VALUES', default='default', cast=Csv())
diff --git a/tests/test_env.py b/tests/test_env.py
index a91c95c..afb3d85 100644
--- a/tests/test_env.py
+++ b/tests/test_env.py
@@ -110,7 +110,7 @@ def test_env_default_none(config):
 
 
 def test_env_empty(config):
-    assert '' == config('KeyEmpty', default=None)
+    assert None is config('KeyEmpty', default=None)
     assert '' == config('KeyEmpty')
 
 
diff --git a/tests/test_ini.py b/tests/test_ini.py
index f610078..15557aa 100644
--- a/tests/test_ini.py
+++ b/tests/test_ini.py
@@ -100,7 +100,8 @@ def test_ini_default_invalid_bool(config):
 
 
 def test_ini_empty(config):
-    assert '' == config('KeyEmpty', default=None)
+    assert None is config('KeyEmpty', default=None)
+    assert '' == config('KeyEmpty')
 
 
 def test_ini_support_space(config):