In [62]: i = pd.MultiIndex( levels=[[u'foo', u'bar'], [u'one', u'two'], [u'a', u'b']], labels=[[0, 0, 1, 1], [0, 1, 0, 1], [1, 0, 1, 0]], names=[u'first', u'second', u'third']) In [63]: s = pd.Series(0, index=i) In [64]: s.unstack([1,2]).stack(0) KeyError: 'Level t not found'