The acquisition of causal knowledge is a primary goal of childhood; yet most of this knowledge is known already to adults. We argue that causal learning which leverages social reasoning is a rapid and important route to knowledge. We present a computational model integrating knowledge about causality with knowledge about intentional agency, but using a domain-general mechanism for reasoning. Inference in this model predicts qualitatively different learning than an equivalent model based on causality alone or a hybrid causal-encoding model. We test these predictions experimentally with adult participants, and discuss the relation of these results to the developmental phenomenon of over-imitation.