  All previous tests of local realism have studied correlations between
single-particle measurements. In the present experiment, we have performed a
Bell experiment on three particles in which one of the measurements corresponds
to a projection onto a maximally-entangled state. We show theoretically and
experimentally, that correlations between these entangled measurements and
single-particle measurements are too strong for any local-realistic theory and
are experimentally exploited to violate a CHSH-Bell inequality by more than 5
standard deviations. We refer to this possibility as "entangled entanglement".
