Matter couplings in N = 2 supergravity

We determine the general coupling of an arbitrary number of massless pin (0, 1 2 ) multiplets to N = 2 supergravity. We find that the matter coupling has a natural description in the language of the supersymmetric non-linear sigma model, where the sigma model is based on a quaternionic manifold. This implies that the matter self-couplings that are allowed in global N = 2 supersymmetry are forbidden in supergravity, and vice versa.