Diesing's main research interests are syntax and the interface between syntax and semantics. Her primary language focus has been the Germanic languages, most notably German and Yiddish. Some of the empirical issues she has concentrated on in recent syntactic work have been argument structure, clause structure, and parameters determining cross-linguistic word order variation. Her work on the syntax/semantics interface centers on the issue of determining the role that syntax plays in deriving the semantic interpretations of noun phrases (including quantifier phrases and pronominals). Among some of the specific issues Diesing is interested in are syntax/semantics interactions in various word order and extraction phenomena, and the syntax and semantics of aspect.