
Raised in the central Massachusetts town of Clinton, Dennis graduated with a BA in English from Clark University, where he met his wife to be, Marty. In the late 1970s, Dennis and Marty moved to Boothbay Harbor, Maine, and ran a freelance editorial business which operated for 20 years. Deciding to transform a long-standing passion into a business, the Gleasons opened Gleason Fine Art, a gallery specializing in late 19th through 21st century art in Boothbay Harbor in 1985. In 2008, the Gleasons opened a second gallery, Gleason Fine Art, Portland, at 545 Congress Street.
Realizing that selling real estate was a natural outgrowth of his love of the midcoast, Dennis earned his real estate license in 2006, associating himself with Blue Water Properties of Rockland, which specializes in fine coastal properties. In 2007 the Gleasons opened the Boothbay Harbor office of Blue Water Properties, which has an office at 31 Townsend Avenue, the same building in which Gleason Fine Art operates. An active community member, Dennis has volunteered for the Boothbay Region Land Trust, the Opera House at Boothbay Harbor, and the YMCA. Currently, he is helping with the Coastal Maine Botanical Gardens capital campaign in Boothbay.