 In 1942, Contreras joined the Women's Army Auxiliary Corps (WAAC) and was sent to Fort Lee, Virginia for training.Contreras volunteered to be part of the 149th WAAC Post Headquarters Company the first to go overseas, setting sail from New York Harbor for Europe on January 1943.She was the first person of Hispanic heritage and the first of approximately 200 Puerto Rican women who would serve in the Women's Army Corps during World War II.