This study examines the acquisition of Catalan and Spanish past-tense verbs (Preterite, Present Perfect, and Imperfect) by children of Moroccan origin in three schools in the Barcelona metropo1itan area. It presents data that allow us to study which of the three tenses poses the most problems for the second language (L2) speakers as compared to the native speakers in a control group. The data were obtained using elicited story-retell tasks and oral narratives. The results show that in both languages acquiring the accurate functional use of verbs is more difficult than making the right lexical or morphological choices. The greatest functional difficulty lies in the acquisition of the Preterite vis-à-vis the Present Perfect. These results provide additional evidence that form precedes function. However, they challenge an established position on the acquisition of tense and aspect in Romance languages, which holds that the most difficult functional feature to acquire for L2 learners of these languages is the difference between perfective and imperfective tenses.