Abstract This paper investigates the L2 acquisition of Spanish object drop by advanced learners whose L1s are English and Brazilian Portuguese, in order to assess effects on their knowledge of the interpretable and uninterpretable features conditioning the realization of object drop in their L2 Spanish. Object drop in Spanish is subject to semantic restrictions related to definiteness and specificity, as well as syntactic restrictions related to subjacency. Current debates about second language acquisition (SLA) have led to different hypotheses. On the one hand, the Interpretability Hypothesis/IH (Hawkins, Roger & Hajime Hattori. 2006. Interpretation of English multiple wh-questions by Japanese speakers: A missing uninterpretable feature account. Second Language Research 22. 269–301) claims that uninterpretable features will not be completely acquired. On the other hand, the Feature Reassembly Hypothesis/FRH (Hwang, Sun Hee & Donna Lardiere. 2013. Plural-marking in L2 Korean: A feature-based approach. Second Language Research 29. 57–86; Lardiere, Donna. 2009. Some thoughts on the contrastive analysis of features in second language acquisition. Second Language Research 25. 173–227) does not distinguish between interpretable and uninterpretable features for the purposes of SLA, arguing that the difficulty of the acquisition task hinges on the required amount of feature reassembly from the L1 to the L2 lexicon. Finally, the Full Transfer/Full Access (FT/FA) (Schwartz, Bonnie & Rex Sprouse. 1996. L2 cognitive states and the Full Transfer/Full Access model. Second Language Research 12. 40–72; Schwartz, Bonnie & Rex Sprouse. 2000. When syntactic theories evolve: Consequences for L2 acquisition research. In John Archibald (ed.), Second language acquisition and linguistic theory, 156–186. Malden, MA: Blackwell; White, Lydia. 2003. Second language acquisition and universal grammar. New York: Cambridge University Press) hypothesis treats SLA as equivalent to first-language acquisition, in terms of the potential for ultimate attainment. Both the FT/FA and the FRH are in principle compatible with full attainment in L2 acquisition. To assess these hypotheses, this study tests the L2 acquisition of the semantic and syntactic restrictions on Spanish object drop by learners whose L1 either lacks widespread object drop (English), or has regular object drop but realizes it differently from Spanish (Brazilian Portuguese). The Full Transfer/Full Access hypothesis seems to best explain the results of the two experiments.