This book brings together some of Griesemers most significant contributions for the first time, making it widely accessible in a single collection. Throughout his career James Griesemer has created an intellectual scaffold for major advances in the history and philosophy of biology. His analyses of boundary objects, units of selection, reproducers, models, and scaffolds have served and continue to serve as sites of innovation for philosophers, historians, and biologists. Griesemer oeuvre does not form a mere collection of important essays on disparate and disconnected topics. His works are best understood as units in a large philosophical puzzle, amounting to an overarching vision of how humans understand life and use that understanding for intervention, which in turn is grounded in a highly sophisticated historical and scientific understanding of the research practices in question. With edits, comments, and an in-depth introduction, this book is of great interest to historians and philosophers of biology as well as science in general.