Languages may differ in the syntactic and semantic information they express overtly and how they express it, morphologically or through other means. These cross-linguistic differences are of paramount importance when acquiring a second language since they affect how the correlations between different forms and meanings are established. In this talk I will show that fine-grained knowledge of how the syntax and semantics properties are represented morphologically in languages is key to understand the process of second language acquisition. Such a refined insight allows us to identify the acquisition task that the learner faces in a precise manner and, correspondingly, contributes to our understanding of issues found in the classroom. A more precise linguistic technical understanding ultimately enables us to address learners’ needs. I will illustrate these points by drawing on my research on grammatical aspect, its cross-linguistic variation and its acquisition in a second language (Arche 2014; Domínguez, Arche & Myles 2017)
