This experimental study investigates the acquisition of Italian accusative and dative clitics by English adult speakers. These pronouns are non-existent in English. Results from a grammaticality judgement task show that Italian accusative and dative clitics develop slowly but gradually in Italian second language (L2) grammars. Interestingly, the placement properties appear to develop earlier than their case properties. The possible implications of these findings for theories of the L2 initial state are considered. (Contains 2 figures and 6 tables.)