The aim of the present study is to empirically test the Aspect Hypothesis (AH), Andersen and Shirai (1994), in Instructed Acquisition of Italian as a Second Language. AH claims that Tense-Aspect morphology acquisition is governed by actional values of verbal predicates. The participants to the present study are represented by a cross-sectional group of English-speakers advanced learners of Italian L2 and adult Italian native speakers as a control group. Subjects have been asked to complete a written fill-in-the-blank task. Data confirm that the instructed acquisition of Italian Tense-Aspect morphology follows the patterns predicted by AH, pointing out a role for Actionality in this process. Instruction appears to accelerate the acquisitional process, without modifying the developmental phases. Didactic suggestions are drawn from these findings. A role for input is currently under dispute and the results show that a distributional bias holds in native speakers production.