Margaret Sanger, the American birth-control and population-control advocate who founded Planned Parenthood, stands like a giant among her contemporaries. With her dominating yet winning personality, she helped generate shifts of opinion on issues that were not even publicly discussed prior to her activism, while her leadership was arguably the single most important factor in achieving social and legislative victories that set the parameters for today’s political discussion of family-planning funding, population-control aid, and even sex education. This work addresses Sanger’s ideas concerning birth control, eugenics, population control, and sterilization against the backdrop of the larger eugenic context.