  In this paper we study M-theory compactifications on seven-dimensional
manifolds with SU(3) structure. As such manifolds naturally pick out a specific
direction, the resulting effective theory can be cast into a form which is
similar to type IIA compactifications to four dimensions. We derive the
gravitino mass matrix in four dimensions and show that for different internal
manifolds (torsion classes) the vacuum preserves either no supersymmetry, or
N=2 supersymmetry or, through spontaneous partial supersymmetry breaking, N=1
supersymmetry. For the latter case we derive the effective N=1 theory and give
explicit examples where all the moduli are stabilised without the need of
non-perturbative effects.
