Born in Montreal, Quebec, he studied art at the Ecole des Beaus-Arts, Montreal, at the age of 26 and afterwards at the Art Association of Montreal where he took figure painting under Edwin Holgate. He enjoyed the rare honour of being invited to exhibit, while still a student, at the Provincial Museum of Quebec in 1939. About this time he was following the work of French painters like Braque and Rouault. He received a scholarship from the Province of Quebec in the earlier part of the year and had the intention of studying in France for four years but the outbreak of the Second World War forced him to change his plans. He was allowed to study on the American continent and he chose New York. Cosgrove arrived in New York with his wife but after two months found it unsatisfactory and finally went to Mexico.
In Mexico he became interested in fresco painting and approached Jose Clemente Orozco through teacher friends. Orozco who had just begun a fresco for the Hospital Jesus de Nazareno in the heart of Mexico City agreed to let him help with parts of the work. Cosgrove arrived each morning at six a.m. To help mix mortar, prepare plaster, and work at everything from cleaning brushed to sweeping floors. On the fresco itself, Cosgrove was allowed to apply flat colours of the background and sketch in the principle points like head, hands and feet, enlarging from Orozco's original sketch.
Orozco himself had learned fresco painting from Italian encyclopedias and advised Cosgrove to go to the Italians for further knowledge of his medium. Cosgrove stayed with Orozco until the completion of the fresco. It was from working with Orozco that Cosgrove felt a new assurance and directness not experiences in his previous work. During his four years in Mexico he also did still lifes, landscapes, street and market scenes.
On his return to Canada in 1944 he concentrated for a time on still lifes, using colours, sometimes with distorted forms and sometimes more representational, showing traces of Braque. Some of his portraits had the characteristic outlines, particularly in the face, of work by Rouault proving highly effective. In 1953, Cosgrove was awarded a Government fellowship to study in France.
Paul Duval in his “Canadian Drawings and Prints” ranked Cosgrove among the gifted of Canadian draughtsmen and used two examples of his drawing for illustration. Dorothy Pfeiffer in a review o Cosgrove's 1961 exhibition at the Dominion Gallery, Montreal, stated, “...The salient qualities of Cosgrove's fresco-like paintings of woody landscapes, still life, portraits and figures studies...would appear to lie in their combined purity and certainty of expression; in their unusual transparency and depth of colour and texture; as well as in a certain mystical sense of detachment from the hurly-burly of everyday life...” His work was also exhibited at the Continental Galleries in Montreal and the Laing Galleries in Toronto.
He was active about 1953 in the field of textile designing, working with a group of artists which included Robert Lapalme, Paul-Emile Borduas, Maurice Raymond and F.C.A. Sullivan. He had also worked for a wider interest in modern fresco painting in Canada, particularly in churches, and he conducted classes in this medium at the Ecole des Beaux Arts. He completes a fresco for the entrance of the philosophy and science wing of the College de Saint Laurent near Montreal.
He is represented in the collections of the Art Gallery of Ontario; Hart House, University of Toronto; the Vancouver Art Gallery and the National Gallery of Canada. He was a member of the Canadian Group of Painters, Royal Canadian Academy (ARCA 1951) and lived in Montreal where he continued to teach at the Ecole des Beaux Arts.
Source: "A Dictionary of Canadian Artists, Volume I: A-F", compiled by Colin S. MacDonald, Canadian Paperbacks Publishing Ltd, Ottawa, 1977
