2How do children and adolescents "make it" when their development is threatened by poverty, neglect, maltreatment, war, violence, or exposure to oppression, racism, and discrimination? What protects them when their parents are disabled by substance abuse, mental illness, or serious physical illness? How do we explain the phenomenon of resilience-children succeeding in spite of serious challenges to their development-and put this knowledge to work for the bene fi t of children and society? The scienti fi c study of resilience emerged around 1970 when a group of pioneering researchers began to notice the phenomenon of positive adaptation among subgroups of children who were considered "at risk" for developing later psychopathology (Masten, 2001(Masten, , 2012 .The resilience research pioneers led a revolution in thinking about the origins and treatment of psychopathology. The primary focus of earlier clinical research on children at high risk for psychopathology had been either to observe the consequences of adversity or the unfolding of risk processes accounting for the etiology of disorders. Research efforts were directed towards understanding pathology and de fi cits, rather than on how problems were averted, resolved, or transcended. The fi eld of mental health at the time was dominated by psychoanalytic theory and a disease-oriented biomedical model that located the source of illness within the individual. However, the fi rst investigators to explore the phenomenon of resilience realized that models based primarily on predicting psychopathology were limited in scope and usefulness, providing little understanding of how good outcomes were achieved by many of the children identi fi ed as "at risk." Such information was vital to the goal of intervening to improve the odds of good developmental outcomes among children at risk. One of the great contributions of the early investigators was their recognition and championing of the idea that understanding positive developmental pathways in the context of adversity is fundamentally important for preventing and treating problems, particularly among children at risk for psychopathology.The study of resilience has advanced in four major waves of research. In this chapter we highlight the concepts and fi ndings resulting from these waves to date, as they have shaped an emerging resilience framework for research and practice. The fi rst wave of work yielded good descriptions of resilience phenomena, along with basic concepts and methodologies, and focused on the individual. The second wave yielded a more dynamic accounting of resilience, adopting a developmental systems approach to theory and research on positive adaptation in the context of adversity or risk, and focused on the transactions among individuals and the many systems in which their development is embedded. The third wave focused on creating resilience by intervention