  We compare a suite of 3D explosion calculations and stellar models
incorporating advanced physics with observational constraints on the progenitor
of Cassiopeia A. We consider binary and single stars from 16 to 40 solar masses
with a range of explosion energies and geometries. The parameter space allowed
by observations of nitrogen rich high velocity ejecta, ejecta mass, compact
remnant mass, and 44Ti and 56Ni abundances individually and as an ensemble is
considered. A progenitor of 15-25 solar masses which loses its hydrogen
envelope to a binary interaction and undergoes an energetic explosion can match
all the observational constraints.
