  We present an efficient method for producing $N$ particle entangled states
using Rydberg blockade interactions. Optical excitation of Rydberg states that
interact weakly, yet have a strong coupling to a second control state is used
to achieve state dependent qubit rotations in small ensembles. On the basis of
quantitative calculations we predict that an N=8 Schr\"odinger cat state can be
produced with a fidelity of 84% in cold Rb atoms.
