According to the aspect hypothesis (Andersen & Shirai, 1996; Bardovi-Harlig, 2000), perfective morphology emerges before imperfective morphology, it is first used in telic predicates (achievements and accomplishments) and it later extends to atelic predicates (activities and states). The opposite development is hypothesized for imperfective morphology. This study proposes to investigate the emergence of preterite and imperfect morphology in Catalan to examine if the aspectual characteristics of predicates can account for the emergence of morphology and also appropriate use. Past verbal forms in narratives produced by three multilingual learners of Catalan as a foreign language were coded for appropriateness of use, morphology, and lexical aspect. An aspectual analysis of the data provided support for the aspect hypothesis, because achievement and accomplishment predicates in general were inflected for preterite morphology more frequently than were activity and state predicates, and the opposite was found for the emergence of imperfect morphology. The aspectual trends, however, varied for individual learners, tasks, and developmental stages. An analysis of the appropriate use of preterite and imperfect forms showed that morphology was used appropriately in almost all contexts. Prototypical combinations of morphology and aspect tended to be used more appropriately than nonprototypical combinations, as supported by other studies (Cadierno, 2000; Camps, 2002; Giacalone-Ramat, 2002).