Dennis received his B.A. in psychology from Northwestern and M.A. and Ph.D. in psychology from Illinois Institute of Technology, concentrating in industrial psychology with a minor in clinical. He worked at a behavioral science consulting firm, doing organizational development, employee satisfaction, employee counseling, training and individual assessment and then developing a research arm focusing on social and market research.

Dennis then founded D.S. Howard & Associates, Inc. to provide consultative market research. That organization has served over 200 major clients in the ensuing years, in healthcare, business-to-business and consumer research. Many of the clients served in the earliest years remain clients to this day.