Adolescence is a remarkable time of growth and development; in just a few years, children transition dramatically towards adulthood across multiple domains. While adolescence is physically the healthiest period of the lifespan, it is also marked by an enormous rise in morbidity and mortality. This seeming paradox can be explained, in part, by biological and psychological changes during puberty that affect emotion regulation, cognition, and consequent risk-taking behavior. At the turn of the twentieth century, adolescence was described as a developmental period inevitably filled with “storm and stress.” In what ways does this vision of adolescence still apply? How should current scientific findings inform our understanding of the propensity for risk-taking behavior during this period (including substance use, increasing sexual activity, and disordered eating)? In exploring the factors that shape emotions, behavior, and emerging identity during adolescence, this course will examine such questions from biological and psychosocial perspectives.