Prosocial and antisocial behaviors can reflect the actor's positive or negative feelings toward a specific person and their broader disposition toward others' welfare. Observers' inferences about these motives shape what they learn about the actor's social relationships and moral character, thereby informing expectations about the actor's future behaviors. In four preregistered studies, we used violation-of-expectation looking methods to investigate 14- and 15-mo-old infants' inferences about social motives by first showing them helping and hindering events and then assessing their expectations for those actors' future actions. If infants use helping and hindering to infer disposition-based motives, they should extend expectations about future helping to others. Alternatively, if they infer relationship-based motives, their expectations should be restricted to the initial interactants. In Experiments 1 and 2, infants first observed two actors, one who helped and another who hindered...