 Forbes was raised in neighboring El Monte and Eagle Rock, where he began his writing career at the high school newspaper.He received his bachelor's degree in Philosophy from University of Southern California in 1953, going on to a Master's in 1955 and a Ph.D. in History and Anthropology (1959).In the early 1960s, Forbes became active as an organizer in the Native American movement, which asserted the rights to sovereignty and resisting assimilation into the majority culture.