Advancing transformative change for sustainability requires population‐wide behavior change. Yet, many behavioral interventions tackling environmental problems only examine average effects on the aggregate, overlooking the heterogeneous effects in a population. We developed and preregistered a novel audience segmentation approach to test the diverse impact of conservation messaging on reducing demand for exotic pets (private action ‐ i.e., desire to own exotic pets or visit wildlife entertainment places) and fostering citizen engagement for system‐wide change (civic action ‐ e.g., signing a petition or participating in a protest against the exotic pet trade). Through an online survey with US participants (n = 2953), we identified 4 population segments (early adopters, early majority, late majority, and laggards), representing varying levels of commitment to wildlife conservation and then randomly assigned each segment to one of 3 messaging conditions. Messages highlighting negative consequences of the exotic pet trade and the power of collective action for system change effectively promoted private action among all segments except early adopters (ηp2 = 0.005). Among civic actions, only the collective action message motivated early adopters and the early majority to sign petitions (φC = 0.193 and φC = 0.097, respectively). Furthermore, the 4 segments showed distinct reasoning for action and inaction on wildlife conservation, with certain relational values, such as care, serving as both motivations and barriers to action. These findings highlight the need for targeted behavioral interventions across diverse populations.