We examined the acquisition of third-person accusative clitics (e.g., lo, la, los, las) in L2 Spanish among Brazilian Portuguese (BP) speakers. In BP, the animacy of the referent is the main feature constraining accusative pronoun use while, in Spanish, animacy does not affect clitic realization. We tested Lardiere’s (2008; 2009) Feature Reassembly Hypothesis (FRH), Schwartz & Sprouse’s (1996) Full Transfer/Full Access hypothesis (FT/FA), and the suitability of productive vocabulary knowledge as a proxy for overall proficiency and its predictive power for the acquisition of clitics. 74 BP-speaking L2 Spanish learners and a comparison group of 23 native Spanish speakers completed a language background questionnaire, a vocabulary test (Prueba Léxica de Español y Portugués/Prova Léxica de Espanhol e Português, PLEP), an elicited production task, and an acceptability judgment task. Only the L2 Spanish participants completed the tasks in both languages. Our findings are consistent with the FRH, showing that the participants successfully disassemble animacy features from their L1 when acquiring the non-animacy-driven clitics in Spanish. However, animacy effects were found in the L2 production data but not in their receptive grammatical knowledge. Furthermore, animacy effects were not dependent on proficiency as no interactions between these factors were found, thus rejecting the existence of a full transfer stage.