I am interested in language acquisition, second language acquisition, morphological and syntactic theory, and developmental linguistics. My recent research focuses on the L2 acquisition of formal aspects of language knowledge (especially morphology and syntax); ultimate attainment, fossilization, and developmental comparisons between child and adult language learning; and the role of linguistic theory in models of first and second language acquisition. I am particularly interested in the nature and acquisition of the mapping between abstract grammatical categories or features and morphophonological form.