The struggle to remove the stigma of sickness surrounding same-sex love has a long history. In 1973, the American Psychiatric Association removed homosexuality from its diagnostic classification of mental illness, but the groundwork for this decision was laid centuries earlier. In this study Henry L. Minton looks back at the struggle of the American gay and lesbian activists who chose scientific research as a path for advocating homosexual rights. He traces the history of gay and lesbian emancipatory research from its early beginnings in the late 19th century to its role in challenging the illness model in the 1970s. By examining archival sources and unpublished manuscripts, Minton reveals the substantial accomplishments made by key researchers and relates their life stories. He also considers the contributions of mainstream sexologists such as Alfred C. Kinsey and Evelyn Hooker who supported the cause through the advancement of scientific knowledge.