More than two decades after E. E. Werner and R. S. Smith (1982), N. Garmezy (1983), and M. Rutter (1987) published their research on protective mechanisms and processes that are most likely to foster resilience, ambiguity continues regarding how to define and operationalize positive development under adversity. This article argues that, because resilience occurs even when risk factors are plentiful, greater emphasis needs to be placed on the role social and physical ecologies play in positive developmental outcomes when individuals encounter significant amounts of stress. Four principles are presented as the basis for an ecological interpretation of the resilience construct: decentrality, complexity, atypicality, and cultural relativity. These 4 principles, and the research upon which they are based, inform a definition of resilience that emphasizes the environmental antecedents of positive growth. This framework can guide future theory development, research, and the design of interventions that promote well-being among populations who experience environments that inhibit resilience-promoting processes.