A key question in second language research concerns the factors that shape learners' ability to understand sentences in real-time. Intuitively, one might think that native grammatical constraints always play a central role. However, an important test case—the processing of agreement with possessive forms like “his" and “her"—reveals that second language processing is sometimes driven more strongly by factors other than native influence. This project seeks to identify these other factors and to address whether the influence of a native language differentially affects second language production and comprehension.