Instead of viewing racial eugenics, modernist religion and prescriptions for social engineering as discourses tangential to the evolution constructs propounded by top scientists in the build-up to the Scopes trial, this article considers how the American Association for the Advancement of Science's committee on evolution intertwined all of these threads by the early nineteen-twenties. Committee members aimed their evolution models at broad public audiences even as they tried to fulfill the American Civil Liberties Union's request to provide a scientifically-sound view of evolution to help combat Protestant fundamentalism in the build-up to the trial. Racialist eugenics was essential to their multi-layered evolution constructs, as were key religious ideas particular to Protestant modernism.