Drawing from Sagarra & Herschensohn (2010, 2011), we evaluate current approaches to grammatical representation and processing of L2 gender and number agreement in Spanish determiner phrases (DPs), some advocating incomplete acquisition and computation of L2 grammatical features and others claiming native-like representation and computation of new grammatical values. Testing Spanish monolinguals, beginning and intermediate L2 learners, we evaluate comprehension data with a moving window paradigm and a grammaticality judgment task to investigate whether late learners of ungendered L1s can gain native-like behavioral patterns of sensitivity to grammatical gender and number agreement violations. We also consider the additional factors of proficiency level (beginners vs. intermediates) and processing cost (animate vs. inanimate nouns; gender vs. number agreement). Moving window and grammaticality judgment data reveal that intermediates, but not beginners, show qualitatively similar reactions to monolinguals (gender and number concord/discord distinctions), confirming the importance of proficiency while suggesting native-like processing by L2 learners. They also show that both grammatical (gender, number) and semantic (animacy) features differentially impact concord processing for both natives and L2 learners, and that working memory plays a role in developing L2 processing skills.