Windsor Hosmer was born in upstate New York in 1894. After two years at Harvard, he interrupted his studies to serve in the Ambulance Corps with the French army in World War I and then returned to graduate in 1919. During the court's investigations he was a graduate student in business and the proctor of Perkins Hall. He earned his Harvard MBA in 1921. He then taught briefly at Harvard Business School before moving to Hobart College. He returned to Harvard in 1931 and became a full professor in 1937. He published several accounting texts and served as an adviser on accounting to the United States Atomic Energy Commission in the 1950s. He set up and helped manage two small businesses and tried to establish a formal program in small business management at Harvard Business School. With two colleagues he published "Small Business Management" in 1966. He retired from teaching in 1963.