I am an applied linguist with expertise in second language acquisition and research methodology. My research focuses on crosslinguistic influence, instruction, and usage-based accounts of learning, with particular interests in instructed grammatical learning and the ways in which cognitive (e.g., blocking, learned attention) and social factors (e.g., integration, immersion) shape development. A major strand of my work in these areas has examined the extent to which instruction can address longstanding learning difficulties that result from crosslinguistic influence. I also have significant interests in replication research. My work here has involved conducting and promoting replication studies as well as providing guidance and training in the design, execution, and interpretation of replication studies. I teach courses on usage-based second language acquisition (APLNG 571), quantitative methods  (APLNG 593), and pedagogical grammar (APLNG 484). I am author of Crosslinguistic Influence and Second Language Learning and, with Graeme Porte, Doing Replication Research in Applied Linguistics. In 2020, I received, with Emma Marsden, the ACTFL-NFMLTA/MLJ Paul Pimsleur Award for Research in Foreign Language Education.

I am an Associate Professor in the Department of Applied Linguistics at Penn State University. I am also Director of the Center for Language Acquisition and Director of the Center for Advanced Language Proficiency Education and Research. I have held previous positions at the University of York (UK) and the University of Southampton (UK).

I am currently an associate editor for Studies in Second Language Acquisition.

I received my PhD in Second Language Acquisition from Newcastle University (UK).