This talk probes the role of luck in the determination of success in the life course. We ask whether when people get lucky the trajectory of their life success increasingly diverges from that of their unlucky counterpart. We study this question theoretically using basic models of positive feedback. Empirically we look at the lives of thousands of Americans tracked in panel survey data and millions of Swedes captured in register data. We focus on income as measure of success and study a host of different ways by which people might be lucky or unlucky at different stages of the life course. We use causal identification strategies to isolate pairs of egos and alteregos who led similarly lives before the event and then compare their life courses afterwards.