This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book presents an overview of current theories of adolescent risk and vulnerability and suggests Youth Development as an overarching framework for understanding both. It discusses Adolescent Health Center's practice of routinely asking mental health clients at intake if they have experienced racism. The book is dedicated to exemplars of practice-based research in action, but other efforts at reilec-tion-in-action conducted over the years have included program design and innovation through client participation in focus groups, practitioner-designed assessment instruments, consumer feedback surveys, etc. Despite popular images of adolescence as a period of mindless fun and self-absorption, adolescents present enormous challenges for health and mental health agencies and are classified as a "population at-risk." Uninsurance rates are higher in minority communities: black and Latino adolescents are much more likely than white adolescents to be uninsured.