Eitan Grossman’s research revolves around the questions why are languages the way they are, and how do they become that way? He is interested in empirical approaches to explanations for linguistic diversity, and conducts research in the framework that has come to be called Distributional Typology, which asks "what's where why (when)?" Ongoing projects include:

• The World Survey of Phonological Segment Borrowing (SEGBO), which explores the typology of phonological segment borrowing and its relevance for evaluating the Uniformitarian Hypothesis;
• BDPROTO, a database of ancient and reconstructed sound systems; 
• The areal typology of sound change; and
• The typology of contact-induced change in a few domains of grammar and lexicon, including valency and transitivity patterns, case markers and adpositions, and verb alternations.

He also works on (or has worked on) the description of Ancient Egyptian-Coptic, Nuer, Spanish, Minangkabau, and Modern Hebrew.

At the Hebrew University, he is currently the head of the Linguistics Department and has served as coordinator of the Functional Linguistics program. He is also a member of the Logic, Language and Cognition Center and the head of the Dynamics of Language Lab. Present and past graduate students and postdocs who belong to this lab work on Quechuan, German language islands, Yiddish, Tibeto-Burman languages, phonological typology, the computational analysis of semantic change in massive corpora, the processing of intonation units, and experimental studies of cognitive biases that may be causal factors in typological distributions.