Resilience in human development is defined in relation to positive adaptation in the context of significant adversity, emphasizing a developmental systems approach. A brief history and glossary on the central concepts of resilience research in developmental science are provided, and the fundamental models and strategies guiding the research are described. Major findings of the first four decades of research are summarized in terms of protective and promotive factors consistently associated with resilience in diverse situations and populations of young people. These factors—such as self-regulation skills, good parenting, community resources, and effective schools—suggest that resilience arises from ordinary protective processes, common but powerful, that protect human development under diverse conditions. The greatest threats posed to children may be adversities that damage or undermine these basic human protective systems. Implications of these findings for theory and practice are discussed, highlighting three strategies of fostering resilience, focused on reducing risk, building strengths or assets, and mobilizing adaptive systems that protect and restore positive human development. The concluding section outlines future directions of resilience research and its applications, including rapidly growing efforts to integrate research and prevention efforts across disciplines, from genetics to ecology, and across level of analysis, from molecules to media.