This book is written by busy clinicians for busy clinicians who need practical tools to work with clients. It includes many case studies, as well as guides to other clinical resources on perfectionism, which is often considered a positive characteristic, including the desire to achieve high standards without negative consequences; but this book emphasizes negativity (anxiety, depression, and eating disorders). The model of "clinical perfection" is understood, describing people who are concerned about their mistakes with extremely high standards; their self-assessment is based on how well these standards are met. This is seen as a crucial component of unhelpful perfectionism, forcing the individual to persevere in the pursuit of meeting their standards. Reassessment of aspirations and achievements is the basis of joint conceptualization, the cornerstone of the book's cognitive-behavioral approach to perfectionism. Suggestions for strengthening the therapeutic alliance and a roadmap for different treatment strategies are given. Designed for clinicians of different specializations; useful for both entry-level doctors and specialists with many years of experience.