diff -r 027494c8ddaf Lib/test/test_tcl.py
--- a/Lib/test/test_tcl.py	Mon Jul 07 15:18:52 2014 +0300
+++ b/Lib/test/test_tcl.py	Tue Jul 08 10:35:55 2014 +0300
@@ -166,7 +166,8 @@
         tcl = self.interp.tk
         self.assertIs(tcl.getboolean('on'), True)
         self.assertIs(tcl.getboolean('1'), True)
-        self.assertEqual(tcl.getboolean(42), 42)
+        self.assertIs(tcl.getboolean(42), True)
+        self.assertIs(tcl.getboolean(0), False)
         self.assertRaises(TypeError, tcl.getboolean)
         self.assertRaises(TypeError, tcl.getboolean, 'on', '1')
         self.assertRaises(TypeError, tcl.getboolean, b'on')
diff -r 027494c8ddaf Lib/tkinter/__init__.py
--- a/Lib/tkinter/__init__.py	Mon Jul 07 15:18:52 2014 +0300
+++ b/Lib/tkinter/__init__.py	Tue Jul 08 10:35:55 2014 +0300
@@ -228,9 +228,11 @@
     def __str__(self):
         """Return the name of the variable in Tcl."""
         return self._name
+    def _sanitize(self, value):
+        return value
     def set(self, value):
         """Set the variable to VALUE."""
-        return self._tk.globalsetvar(self._name, value)
+        return self._tk.globalsetvar(self._name, self._sanitize(value))
     initialize = set
     def get(self):
         """Return value of variable."""
@@ -344,6 +346,9 @@
         """
         Variable.__init__(self, master, value, name)
 
+    def _sanitize(self, value):
+        return self._tk.getboolean(value)
+
     def get(self):
         """Return the value of the variable as a bool."""
         try:
diff -r 027494c8ddaf Lib/tkinter/test/test_tkinter/test_variables.py
--- a/Lib/tkinter/test/test_tkinter/test_variables.py	Mon Jul 07 15:18:52 2014 +0300
+++ b/Lib/tkinter/test/test_tkinter/test_variables.py	Tue Jul 08 10:35:55 2014 +0300
@@ -1,6 +1,7 @@
 import unittest
 
-from tkinter import Variable, StringVar, IntVar, DoubleVar, BooleanVar, Tk
+from tkinter import (Variable, StringVar, IntVar, DoubleVar, BooleanVar, Tk,
+                     TclError)
 
 
 class Var(Variable):
@@ -159,16 +160,41 @@
 
     def test_default(self):
         v = BooleanVar(self.root)
-        self.assertEqual(False, v.get())
+        self.assertIs(v.get(), False)
 
     def test_get(self):
         v = BooleanVar(self.root, True, "name")
-        self.assertAlmostEqual(True, v.get())
+        self.assertIs(v.get(), True)
         self.root.globalsetvar("name", "0")
-        self.assertAlmostEqual(False, v.get())
+        self.assertIs(v.get(), False)
+        self.root.globalsetvar("name", 42 if self.root.wantobjects() else 1)
+        self.assertIs(v.get(), True)
+        self.root.globalsetvar("name", 0)
+        self.assertIs(v.get(), False)
+        self.root.globalsetvar("name", "on")
+        self.assertIs(v.get(), True)
+
+    def test_set(self):
+        true = 1 if self.root.wantobjects() else "1"
+        false = 0 if self.root.wantobjects() else "0"
+        v = BooleanVar(self.root, name="name")
+        v.set(True)
+        self.assertEqual(self.root.globalgetvar("name"), true)
+        v.set("0")
+        self.assertEqual(self.root.globalgetvar("name"), false)
+        v.set(42)
+        self.assertEqual(self.root.globalgetvar("name"), true)
+        v.set(0)
+        self.assertEqual(self.root.globalgetvar("name"), false)
+        v.set("on")
+        self.assertEqual(self.root.globalgetvar("name"), true)
 
     def test_invalid_value_domain(self):
+        false = 0 if self.root.wantobjects() else "0"
         v = BooleanVar(self.root, name="name")
+        with self.assertRaises(TclError):
+            v.set("value")
+        self.assertEqual(self.root.globalgetvar("name"), false)
         self.root.globalsetvar("name", "value")
         with self.assertRaises(ValueError):
             v.get()
diff -r 027494c8ddaf Lib/tkinter/ttk.py
--- a/Lib/tkinter/ttk.py	Mon Jul 07 15:18:52 2014 +0300
+++ b/Lib/tkinter/ttk.py	Tue Jul 08 10:35:55 2014 +0300
@@ -582,7 +582,7 @@
         if ret and callback:
             return callback(*args, **kw)
 
-        return bool(ret)
+        return ret
 
 
     def state(self, statespec=None):
@@ -690,7 +690,7 @@
         """Force revalidation, independent of the conditions specified
         by the validate option. Returns False if validation fails, True
         if it succeeds. Sets or clears the invalid state accordingly."""
-        return bool(self.tk.getboolean(self.tk.call(self._w, "validate")))
+        return self.tk.getboolean(self.tk.call(self._w, "validate"))
 
 
 class Combobox(Entry):
@@ -1240,7 +1240,7 @@
     def exists(self, item):
         """Returns True if the specified item is present in the tree,
         False otherwise."""
-        return bool(self.tk.getboolean(self.tk.call(self._w, "exists", item)))
+        return self.tk.getboolean(self.tk.call(self._w, "exists", item))
 
 
     def focus(self, item=None):
diff -r 027494c8ddaf Modules/_tkinter.c
--- a/Modules/_tkinter.c	Mon Jul 07 15:18:52 2014 +0300
+++ b/Modules/_tkinter.c	Tue Jul 08 10:35:55 2014 +0300
@@ -1733,15 +1733,21 @@
 static PyObject *
 Tkapp_GetBoolean(PyObject *self, PyObject *args)
 {
+    PyObject *arg;
     char *s;
     int v;
 
-    if (PyTuple_Size(args) == 1) {
-        PyObject *o = PyTuple_GetItem(args, 0);
-        if (PyLong_Check(o)) {
-            Py_INCREF(o);
-            return o;
-        }
+    if (!PyArg_ParseTuple(args, "O:getboolean", &arg))
+        return NULL;
+    if (PyLong_Check(arg)) { /* int or bool */
+        return PyBool_FromLong(PyObject_IsTrue(arg));
+    }
+    if (PyTclObject_Check(arg)) {
+        if (Tcl_GetBooleanFromObj(Tkapp_Interp(self),
+                                  ((PyTclObject*)arg)->value,
+                                  &v) == TCL_ERROR)
+            return Tkinter_Error(self);
+        return PyBool_FromLong(v);
     }
     if (!PyArg_ParseTuple(args, "s:getboolean", &s))
         return NULL;