This paper investigates whether ne-cliticisation with intransitive verbs in Italian, a phenomenon relating to the lexicon-syntax interface, can be fully acquired in the L2. It reports the findings of an experimental study in which a group of highly proficient adult L2 learners of Italian, who are native speakers of Croatian, a language without ne-cliticisation, and a group of Italian native speakers performed an acceptability judgement task with Magnitude Estimation as the elicitation procedure. In the study, the L2 learners proved able to make syntactic and subtle lexical-semantic distinctions relevant for ne-cliticisation with intransitive verbs to a statistically significant degree. This suggests that they have acquired both the syntactic and the lexical-semantic properties of the phenomenon. Such findings are consistent with the proposal according to which phenomena pertaining to internal interfaces, which connect syntax and other domains within the language faculty, such as the lexicon, are acquirable in the L2.