This article describes a social-ecological approach for promoting and enhancing self-determination among individuals with developmental disabilities. A five-level model is presented, based on the interaction of person and environmental factors, that identifies a series of social mediator variables (i.e., social effectiveness, social capital, social inclusion), which the authors believe can successfully influence self-determination improvement efforts and enhance the efficacy of self-determination interventions. The impact of these mediators on intervention outcomes is considered within an interactional, social-ecological context of person-specific (individual characteristics) and environment-specific (provision of opportunities to make choices) contexts. This approach will guide the activities of a five-year National Training Consortium on self-determination involving five universities and funded by the U.S. Administration on Developmental Disabilities. The expected long-term outcomes associated with this initiative include "improved self-determination options," "greater social inclusion," "and enhanced quality of life" for people with developmental disabilities. (Contains 3 figures.)