Evolutionary psychology presupposes relations between theories of different domains that the two traditional models, reduction and autonomy, cannot properly account for. We aim to construct a model of relations between theories that succeeds where traditional models fail. We show that the multiple realizability argument, on which the autonomist model is thought to rest, is compatible with reductionism and, following Kim, that an autonomist reading of the argument deprives psychology of its scientific status. We therefore opt for a reductionist model compatible (...) with functionalism and multiple realizability, but show that, within evolutionary psychology at least, the very application of the conditions of reduction requires strong interactions between psychology and various other adjacent disciplines. We also show that reduction must be preceded in evolutionary psychology by an of the reduction base, which brings still other disciplines into play. Finally, we present a model of the interaction between disciplines we believe accounts best for these relations and discuss the problems facing this kind of enterprise. (shrink)