Using two case studies, Dr. Peter Blos provides insight on the foundations of later adolescent development, commenting on the psychoanalytic theory and practice of understanding the teenage years. Through his extensive clinical experience with adolescents, Dr. Peter Blos has come to consider the early years of adolescence the most crucial ones because they lay the foundation for later adolescent development. Fixations in the early phases of adolescence give rise to deviant developments which the two case studies of this volume richly illuminate. Susan and Ben were both successfully treated, and these insightful analyses of their treatment form a major contribution to psychoanalytic theory and practice.