Dennis began his studies in high school and then went to Butera School of Art in Boston. He returned to Cape Ann to become the first student studying the Atelier System with John C. Terelak and Ted Goerschner at the newly formed Gloucester Academy of Fine Arts. Later he moved to New York City to study at the Arts Student League, winning the Charles J. Romans Memorial Award at his very first national exhibit at the Allied Artists of America Show. Dennis returned to Cape Ann in 1980 to teach at the Academy. Later he painted with Don Stone and helped teach classes in Monhegan with him.

Dennis is a member of many prestigious art associations including the Oil Painters of America, North Shore Arts Association, Rockport Art Association, the Copley Society of Art (a Copley Artist), the Hudson Valley Arts Association, and the Academic Artists Association.

Dennis stays close to the sea drawing inspiration from meadows, forests, and the coast from Cape Ann to Maine. Dennis believes painting nature provides him clear communication with all that is divine. He considers it a challenge to try to capture a moment in time in his plein air painting. The changing light, movement, moods, and the colors of the world allow him to share his responses to nature with his viewers. “People may pass this way every day,” says Dennis, “and not notice the essence of place until they see it captured on canvas.”