This article examines the process of acquisition of relative clauses in second language (L2) Italian. Despite the fact that linguistic research clearly evidences a distinction between restrictive relative clauses and non-restrictive relative clauses, second language acquisition studies have so far investigated the acquisition of relative clauses disregarding this fundamental and functional difference. Based on the analysis of oral data of 96 L2 Italian students of two different Common European Framework of Reference proficiency levels (B1 and C2), this study examines occurrences of target language relative clauses and of other strategies of relativization (i.e. coordinated sentences), analysing proficiency and first language (L1) influence on distribution. The significant differences in the distribution of alternative relativization strategies between the two groups and the non-restrictive function of coordinated sentences lead to the hypothesis that there are two distinct patterns of acquisition: one for restrictive and another for non-restrictive relative clauses. (Contains 6 notes, 11 tables, and 4 figures.)