Harry Hamilton Laughlin helped lead the eugenics movement in the United States during the early twentieth century. The US eugenics movement of the early twentieth century sought to reform the genetic composition of the United States population through sterilization and other restrictive reproductive measures. Laughlin worked as superintendent and assistant director of the Eugenics Research Office (ERO) at Cold Spring Harbor Laboratory in Cold Spring Harbor, New York, alongside director Charles Davenport. During Laughlin's career at the ERO, Laughlin studied human familial ancestry, called pedigrees, and in 1922 published the book Eugenical Sterilization in the United States, which influenced sterilization laws in multiple states. Laughlin's support of compulsory sterilization to control the reproductive capacity of entire populations influenced the history of eugenics and reproductive medicine.