While environmental action is recognized as an effective approach for developing young people's capabilities as citizens and contributing to environmental improvements, little research has addressed how adults facilitate youth action projects. Environmental action involves a partnership among youth and adults characterized by shared decision-making. We sought insights into the adult experience of shared decision-making through phenomenological interviews with 33 educators facilitating youth environmental action in various non-formal and formal settings in the USA. Educators described experiencing tensions in sharing decision-making power, which we conceive of as a duality--two inseparable elements both contradictory and complementary that drive the dynamics of a system. The duality consists of youth autonomy and adult authority, which stems not only from formally vested decision-making power but also adults' experience and wisdom. Educators navigated this duality through diverse approaches to structuring youth participation, supporting youth, valuing mutual learning, and communicating transparently to develop equitable relationships.