Spain has become one of the most prominent fertility markets in the world, largely fuelled by the availability of human eggs. Behind the promise of cutting-edge technology and parenthood lies a carefully tailored system to recruit, manage, and discipline egg donors. In this book, Anna Molas explores how young women are incorporated as egg donors into the global reproductive industry. Through in-depth ethnographic fieldwork with both donors and clinicians, the book reveals the fragile processes of selection, monitoring, and control that ensure the supply of human eggs. Introducing the concept of taming, Molas illuminates the gendered, racialized, and classed dimensions of reproductive labor. Engaging with the political economy of reproduction and the future of reproductive medicine, this book is an essential resource for scholars in medical anthropology, Science and Technology Studies, and feminist studies. Anna Molas is a Lecturer in Anthropology at Monash University, Australia, and former Juan de la Cierva Fellow at the Autonomous University of Barcelona, Spain. Her research focuses on assisted reproduction, biotechnologies, environmental reproductive health, and feminist STS. In 2023, she received the ISRF First Book Grant to develop this manuscript.