Book excerpt: This book can be used to provide insight into this important application of biophysics for those who are planning a career in protein therapeutic development, and for those outside this area who are interested in understanding it better. The initial chapters describe the underlying theory, and strengths and weaknesses of the different techniques commonly used during therapeutic development. The majority of the chapters discuss the applications of these techniques, including case studies, across the product lifecycle from early discovery, where the focus is on identifying targets, and screening for potential drug product candidates, through expression and purification, large scale production, formulation development, lot-to-lot comparability studies, and commercial support including investigations.