This volume traces the complicated paths through which physiological approaches to reproduction led to endocrinological approaches, creating along the way new technoscientific products from contraceptives to hormone therapies to new modes of assisted conception - for both humans and animals. The author focuses on the changing relations and often uneasy collaborations among scientists and the key social worlds most interested in their work - major philanthropists and a wide array of feminist and medical birth control and eugenics advocates - and recounts how the reproductive sciences slowly acquired standing.