In the early 1970s, the environmental movement was underway. Overpopulation was recognized as a threat to human well-being, and scientists like Michael Soul believed there was a connection between anthropogenic pressures on natural resources and the loss of the planet's biodiversity. Soul-thinker, philosopher, teacher, mentor, and scientist-recognized the importance of a healthy natural world and with other leaders of the day pushed for a new interdisciplinary approach to preserving biological diversity. Thirty years later, Soul is hailed by many as the single most important force in the development of the modern science of conservation biology. This book is a select collection of seminal writings by Michael Soul over a thirty-year time-span from 1980 through the present day. Previously published in books and leading journals, these carefully selected pieces show the progression of his intellectual thinking on topics such as genetics, ecology, evolutionary biology, and extinctions, and how the history and substance of the field of conservation biology evolved over time. It opens with an in-depth introduction by marine conservation biologist James Estes, a long-time colleague of Soul's, who explains why Soul's special combination of science and leadership was the catalyst for bringing about the modern era of conservation biology. Estes offers a thoughtful commentary on the challenges that lie ahead for the young discipline in the face of climate change, increasing species extinctions, and impassioned debate within the conservation community itself over the best path forward. Intended for a new generation of students, this book offers a fresh presentation of goals of conservation biology, and inspiration and guidance for the global biodiversity crises facing us today. Readers will come away with an understanding of the science, passion, idealism, and sense of urgency that drove early founders of conservation biology like Michael Soul.