Prior research has shown that young infants understand something about others' goals. This understanding has been developmentally linked to infants' own actions. An open question is what aspects of experience are crucial to action understanding. In the current studies, we sought to examine the relation between experience and action understanding in 3-month-old infants and to investigate the differential effects of active and passive experience. Findings from Study 1 demonstrated a threshold effect: a minimal amount of active experience led to subsequent action understanding. In Study 2, we assessed whether visual experience alone would have the same effect by giving another group of infants matched passive experience. These infants, however, did not reap the same benefits from passive experience. These findings demonstrate that active experience provides important information, above and beyond that which can be gleaned from passive experience, at a time when intention understanding is first emerging.