Paul Bowman Popenoe was a researcher, writer, and social advocate who studied breeding in the United States during the twentieth century, first in plants and then in humans. Popenoe advocated for eugenic policies in California and beyond in the early twentieth century, and he introduced and promoted marriage counseling as a professional service in the US during the mid-twentieth century. The US eugenics movement, in which Popenoe participated, was a scientific and political project in which eugenicists attempted to improve human populations through selective breeding. Participants of the movement often advocated for the implementation of compulsory sterilization laws for certain “undesirable” populations. Though largely disavowed as of 2026, eugenics persisted well into the twentieth century. Through dozens of publications and a lifetime of public advocacy, Popenoe supported policies that led to the forced sterilization of thousands of people in California and popularized counseling as an intervention into people’s marriages and reproductive choices.