In the mid-1960s, Daniel Offer made his mark on the field of psychopathology with an important study of ordinary adolescents. Counter to the prevailing view that normal adolescence is characterized by turmoil and upheaval, he found that the norm was stability provided that the rearing was in “an average expectable environment.” In the four decades since Offer’s landmark study, clinicians have come to appreciate that his arguments were correct, no longer representing controversy. However, additional research has shown that the adolescent age period does index a range of important changes. This paper considers the implications for theory and practice since Offer’s research more than four decades ago. Through a review of research, this paper reviews the overall features of adolescence, the psychopathological changes in adolescence, and brain development during adolescence. The possible pathways involved in adolescent transitions are considered with respect to depression, drug use/abuse, antisocial behavior, schizophrenia, and suicidal behavior. Conclusions are drawn on the operation of a range of multi-step causal pathways and implications for policy and practice are discussed. References