Much of my research has been devoted to the study of the nature, organization, and use of lexical knowledge. Because lexical knowledge encompasses both morphological, syntactic, and semantic information, I have been concerned with morphological issues (e.g., construction-based morphology), interface issues (e.g., argument structure, the syntax of aspect), and semantic issues (lexical and grammatical aspect, (in)definiteness, negation, semantic similarity). I am a language scientist, which means I approach issues from a variety of perspectives, traditional linguistic analysis, corpus linguistics, psycholinguistics, and cognitive science more generally. 
Over the years, thanks to my former students and colleagues, I have have had the privilege to work on many languages, including English, French, Hindi, Japanese, Mandarin, Spanish, and Thai. For over a decade, I have been collaborating with Karin Michelson on the morphology, syntax, and semantics of Oneida (Northern Iroquoian) and we have been discovering and re-discovering the intricacies of a remarkable language that challenged my preconceptions about linguistic diversity. Some of the topics we have worked and published on includes kinship terms, parts-of-speech, argument (non-)realization, inflectional morphology, "verb" to "noun" conversion, negation, body-parts, possession, and quantification.