In Yellowstone National Park, the National Park Service (NPS) is legally obligated to preserve ecological health and promote recreation. These two mandates have been interpreted differently over the course of NPS management, and these changing interpretations have altered the park's ecosystems. We use a branch of political economy known as public choice analysis to explore how and why management regimes in Yellowstone have changed over time. We also examine what the ecological effects have been from these management changes.