This thesis explores how concepts of "adolescence" and "adolescent psychopathology" have become salient among medical and lay communities in Pelotas, a small town in Rio Grande do Sul, Brazil's southernmost state. The concept of adolescence emerged throughout the 20th century in Western Europe and North America from various specialized fields, including evolutionary medicine, psychiatry, and developmental psychology. Within these sub-fields, adolescence came to refer to a transitional phase in the life span, and specifically, to the psychopathologies and psychological opportunities ensuing from what could potentially become a life-altering transformation. In the past two decades, this concept of adolescence has been adopted by a number of global health agencies, who depict the adolescent phase as an opportunity for addressing the underlying causes of multiple psychopathologies and accordingly, for improving the developmental "health" of nations. Concepts and practices relating to the management of adolescent psychopathology readily took hold in Pelotas in the 1990s, not only because local professional communities have been seeped in a psychoanalytic tradition dating back to the early 20th century, but also because of a recent growing community-based health care movement that prompted the expansion of publicly funded mental health services. This expansion widened definitions of "therapy" to include preventive care and social mobilization, and impacted significantly the identity, social role and political inclinations of practitioners. Due to these changes, psychiatrists and psychologists are showing greater interest in adolescent patients and their various common mental disorders, including "aggressiveness," nervos, anxiety, and learning and school achievement problems. Yet several social and class struggles ensue when practitioners, many of whom seek to maintain their psychodynamic models relatively intact, shift the focus of their work