This paper explores experiences that remained salient in the memories of former participants in three nature-based programs in Colorado, five to forty years after childhood involvement. Interviews with program founders and staff, archival research, and observations of current activities provided an understanding of each program's history, mission and educational approach. In this context, 18 former participants were interviewed about program experiences that they remembered and program impacts on their environmental identities and academic or career choices. Results were analyzed through the lens of social practice theory, which has significant implications for the design and evaluation of environmental education programs. Results showed that social practice theory is a useful framework for interpreting the development of a social environmental identity, but an ecological identity that forms through direct contact with the natural world is an important complementary concept.