Cy DeCosse was born in 1929 in Valley City, North Dakota and graduated from the Minneapolis College of Art and Design in 1952. DeCosse began his career working at a Minneapolis advertising agency as a junior art director. In order to better understand photography, DeCosse bought his first camera and turned the coal cellar in his basement into a darkroom, and began photographing everything around him. In 1954 he won a Fulbright scholarship and he was sent to Florence to help set up an advertising educational program at the Instituto d’Arte di Porta Romana. While there, he also studied with Renzo Maggini, a gifted teacher at Porta Romana who provided DeCosse’s only formal photographic instruction.
Upon returning to Minnesota, DeCosse resumed his career in advertising, becoming an art director and later a Vice President of Campbell-Mithun Advertising. In 1969 DeCosse formed his own firm, which offered creative services for marketing and later expanded into book publishing. Before and after the sale of his company in 1994, DeCosse returned to his passion for photography and began exploring the traditional process of platinum printing intensely for two years. In 2001, with Keith Taylor as the printer, they began a revival of the gum dichromate technique, an alternative process that produces a color print of extraordinary beauty.