This book is about the science and ethics of clinical research and healthcare. We provide an overview of each chapter in its three sections. The first section reviews foundational knowledge about clinical research. The second section provides background and critique on key components and issues in clinical research, ranging from how research questions are formulated, to how to find and synthesize the research that is produced. The third section comprises four case studies of widely used evaluations and treatments. These case examples are exercises in critical thinking, applying the questions and methods outlined in other sections of the book. Each chapter suggests strategies to help clinical research be more useful for clinicians and more relevant for patients.