O'Hara attended Norwich University in Vermont for one year before going in 1910 to a hotel management school in Paris. While in Paris he pursued his interest in painting with his Waltham friend Russell Hyde. When his father died in 1912, he returned home to take over the family business, the O'Hara Dial Company, which he managed until 1927, when a Guggenheim traveling fellowship enabled him to return to Europe for two years to concentrate on his painting. In 1931, O'Hara founded a school and watercolor gallery at Goose Rocks Beach near Kennebunkport, Maine, which he operated until it was destroyed by fire in 1947.
Among O'Hara's books on the technique of watercolor painting are: Making Watercolor Behave, 1932; Making the Brush Behave, 1935; and Art Teacher's Primer, 1939 (all published by Minton Balch & Co., New York). He taught widely at museums and universities and established various schools around the country. Milch Galleries handled his work in New York. When the Academy introduced the watercolorist membership classification in 1944, he was among the first group of painters in this medium to be elected to membership.
O'Hara wrote the secretary of the Academy, November 27, 1944, that Adams had done this portrait "just after Election Day," but would like to keep it for a while for possible exhibition--if it would not delay confirmation of O'Hara's election to Associate.