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). He was Department Chair twice and was frequently a leader in Rhetoric's Professional Development Program (PDP). He did frequent service to the college and university including the General Education Advisory Committee, Student Appeals Committee, and Student Success Team.

His research centered on Renaissance studies, with publications on Elizabethan political poetry and the sixteenth-century controversy over whether a woman could rightfully rule England. He 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 and retired in June 2010.