In earlier work, we applied a causal Bayes net approach to instances of physical causality, like the "blicket detector". But children's theories of psychological causality are equally if not more important. I will report several studies that investigate the role of causal learning in psychological understanding. In one series of studies we explore how children use causal learning to segment human action into meaningful units. Ina second series we explore the relation between imitative learning and causal learning. And in a final set of studies we explore how causal learning plays a role in the development of children's attributions of actions to either situations or traits.