This chapter reviews the research on environmental exemplars, or activists. General themes that have been identified in the literature include early experiences in nature, the influence of other people and organizations, opportunities for environmental education, environmental self and identity formation, and generativity. With these themes in hand, we construct a developmental model suggesting a possible trajectory toward environmental activism. We also discuss possible implications of these findings with reference to the current state of our planet and what may be done to reverse current trends. © 2013 Wiley Periodicals, Inc.