In a number of studies, the acquisition of restrictive relative clauses (RCs) shows contrasting findings regarding comprehension and production, with the former usually delayed up to the age of five. As previously claimed in the literature, we suggest that this delay is a task artifact and we present a new procedure for the assessment of restrictive RCs. Data from three- to seven-year-old Italian children were collected and results show that children understand object RCs with preverbal subject in an adult-like manner at four years of age, but some of the three-year-old children were already above chance. Subject relatives show at ceiling performance from three years of age. We consider our results as evidence of continuity between early and adult competence grammars. Children's non-target responses are interpreted as grammatical options exploited by an immature performance system.