Before coming to Iowa, Dennis was a postdoctoral intern in linguistics and the teaching of writing at Temple University (Philadelphia) and a Mellon Fellow in the Department of English and the Literature and History Program at Washington University (St. Louis).

In June 2008, Dennis began serving as Department Chair, an office he also held about twenty years ago. He has frequently been a leader in Rhetoric's Professional Development Program (PDP). Current service to the College and University includes the General Education Advisory Committee, Student Appeals Committee, and Student Success Team.

His research centers on Renaissance studies, with publications on Elizabethan political poetry and the sixteenth-century controversy over whether a woman could rightfully rule England. He has taught a variety of courses in the Department of English, from an undergraduate survey of Renaissance drama to a graduate seminar on theories of language and the teaching of writing.