Alexander Brook was born in Brooklyn, New York. He entered the Art Student's League where he studied for four years. From 1924-27 he was the assistant director of Whitney Studio Club, which became the Whitney Museum of American Arts in 1931. His realist painting was exhibited widely and he won multiple awards throughout the decade. In 1938, he began a long association with Savannah, and used his observations as the basis for several major works depicting the lives of the impoverished Afrian-Americans living in the region. In 1948, Brook moved to Sag Harbor, New York where he lived for the rest of his life.