Born in Montreal, Quebec, Cosgrove studied painting at l'Ecole des Beaux-Arts in Montreal under Charles Maillard, Henri Charpentier and Joseph Saint-Charles (1928-35) and at the Art Association of Montreal under Edwin Holgate (1936). during this period he was influenced by French artists Georges Barque and Georges Rouault. He received a Quebec Provincial Scholarship to study in Europe for four years, but, with the outbreak of the Second World War he chose Mexico instead. While in Mexico he became interested in, and worked on fresco paintings, as well as still life, landscapes and street scenes. he returned to Canada in 1944 and concentrated for a while on still life and portraits, some more representational than others. Later he started fresco-style paintings of tree-lined and wooded landscapes, still life, figure studies and portraits. he taught art at l'Ecole des Beaux-Arts in Montreal (1944-70). he exhibited at the RCA between 1950-54, and the MMFA between 1936-64. His work is represented in UOT, VAG, AGO, the NGC and MOMA.