Simeon Moss was born and raised in Princeton, New Jersey. He went to Witherspoon School and Princeton High School, graduating in 1937. As an undergraduate at Rutgers, he participated in ROTC, played 150-pound football and lacrosse, and was a member of Alpha Phi Alpha fraternity. He graduated from the Rutgers School of Education in 1941. After being drafted during World War II, he served as an officer in an all-Black unit in the 92nd Infantry Division in the European Theater of Operations. Moss was awarded the Silver Star and Bronze Star, as well as the Purple Heart after being wounded by a shell burst in Italy. He went to graduate school on the GI Bill, becoming the first African American to earn a graduate degree at Princeton University. He was called up for service during the Korean War and thereafter served in the New Jersey National Guard. During his career, he worked as an educator and administrator in New Jersey. Active in civil rights, he served in the Mercer County branch of the NAACP.