diff --git a/.gitignore b/.gitignore
index 3f8a666..fce3abb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,4 @@
 /dist/
 /tmp/
 /.cache/
+/.idea/
\ No newline at end of file
diff --git a/boolean/boolean.py b/boolean/boolean.py
index 369f074..22e0543 100644
--- a/boolean/boolean.py
+++ b/boolean/boolean.py
@@ -26,12 +26,21 @@
 
 import inspect
 import itertools
+from operator import and_ as and_operator
+from operator import or_ as or_operator
+
 
 try:
     basestring  # Python 2
 except NameError:
     basestring = str  # Python 3
 
+try:
+    reduce  # Python 2
+except NameError:
+    from functools import reduce  # Python 3
+
+
 # Set to True to enable tracing for parsing
 TRACE_PARSE = False
 
@@ -849,6 +858,10 @@ def __init__(self, obj):
         self.iscanonical = True
         self.isliteral = True
 
+    def __call__(self, **kwargs):
+        """ returns the value for this symbol from kwargs """
+        return kwargs[self.obj]
+
     def __hash__(self):
         if self.obj is None:  # Anonymous Symbol.
             return id(self)
@@ -1052,6 +1065,10 @@ def demorgan(self):
         op = expr.args[0]
         return op.dual(*(self.__class__(arg).cancel() for arg in op.args))
 
+    def __call__(self, **kwargs):
+        """ negates the value returned from self.args[0].__call__ """
+        return not self.args[0](**kwargs)
+
     def __lt__(self, other):
         return self.args[0] < other
 
@@ -1407,6 +1424,14 @@ def __init__(self, arg1, arg2, *args):
         self.dual = self.OR
         self.operator = '&'
 
+    def __call__(self, **kwargs):
+        """
+        Calls arg.__call__ for each arg in self.args and applies python 'and' operator.
+
+        reduce is used as in e.g. AND(a, b, c, d) == AND(a, AND(b, AND(c, d)))
+        """
+        return reduce(and_operator, (a(**kwargs) for a in self.args))
+
 
 class OR(DualBase):
     """
@@ -1430,3 +1455,11 @@ def __init__(self, arg1, arg2, *args):
         self.annihilator = self.TRUE
         self.dual = self.AND
         self.operator = '|'
+
+    def __call__(self, **kwargs):
+        """
+        Calls arg.__call__ for each arg in self.args and applies python 'or' operator.
+
+        reduce is used as in e.g. OR(a, b, c, d) == OR(a, OR(b, OR(c, d)))
+        """
+        return reduce(or_operator, (a(**kwargs) for a in self.args))
diff --git a/boolean/test_boolean.py b/boolean/test_boolean.py
index fa9fbf8..5001fe9 100644
--- a/boolean/test_boolean.py
+++ b/boolean/test_boolean.py
@@ -1073,5 +1073,51 @@ def __init__(self, name, value='value'):
             self.fail(e)
 
 
+class CallabilityTestCase(unittest.TestCase):
+
+    def test_and(self):
+        algebra = BooleanAlgebra()
+        exp = algebra.parse("a&b&c")
+        for a in [True, False]:
+            for b in [True, False]:
+                for c in [True, False]:
+                    self.assertEqual(exp(a=a, b=b, c=c), a and b and c)
+
+    def test_or(self):
+        algebra = BooleanAlgebra()
+        exp = algebra.parse("a|b|c")
+        for a in [True, False]:
+            for b in [True, False]:
+                for c in [True, False]:
+                    self.assertEqual(exp(a=a, b=b, c=c), a or b or c)
+
+    def test_not(self):
+        algebra = BooleanAlgebra()
+        exp = algebra.parse("!a")
+        for a in [True, False]:
+            self.assertEqual(exp(a=a), not a)
+
+    def test_symbol(self):
+        algebra = BooleanAlgebra()
+        exp = algebra.parse("a")
+        for a in [True, False]:
+            self.assertEqual(exp(a=a), a)
+
+    def test_composite(self):
+        algebra = BooleanAlgebra()
+        exp = algebra.parse("!(a|b&(a|!c))")
+        for a in [True, False]:
+            for b in [True, False]:
+                for c in [True, False]:
+                    self.assertEqual(exp(a=a, b=b, c=c), not(a or b and (a or not c)))
+
+    def test_negate_A_or_B(self):
+        algebra = BooleanAlgebra()
+        exp = algebra.parse("!(a|b)")
+        for a in [True, False]:
+            for b in [True, False]:
+                self.assertEqual(exp(a=a, b=b), not(a or b))
+
+
 if __name__ == '__main__':
     unittest.main()