This book outlines our unique conceptualization of perfectionism, as well as assessment and treatment approaches for it. It represents the culmination of over two decades of research and clinical work on this topic. Our primary purpose for writing this book is to offer insight into the complex construct of perfectionism—not only as a personality style involving traits and relational elements, but also as a clinically relevant personality vulnerability factor that predisposes individuals to myriad problems. We also provide information on appropriate assessment and treatment of those people who are paying a signifcant personal price for their perfectionism.