Endicott Peabody holds an A.B. in history from Harvard College and a J.D. from Harvard Law School. He served in the United States Navy during World War II, earning a Silver Star. Peabody spent several years in public service roles before being elected Governor of Massachusetts in 1962. During his tenure, he championed policies against housing discrimination, established drug addiction treatment programs, and opposed capital punishment. Peabody's commitment to civil rights was underscored by his mother's arrest in 1964, which highlighted the racial segregation issues of the time.

Endicott Peabody's political identity is marked by a surprising convergence of progressive civil rights advocacy and a staunch opposition to capital punishment, coupled with a commitment to economic and educational reforms. His legislative actions, such as preventing housing discrimination and establishing drug addiction treatment programs, reveal a nuanced approach to social justice. Peabody's refusal to sign death warrants and recommendation of commutations for death sentences further highlight his principled stance against capital punishment, even amidst a politically charged era.