Environmental sustainability is a strategic and ethical imperative for organizations, and numerous studies have investigated associations between leadership and employee pro-environmental or “green” behavior. However, these studies have typically focused on leadership styles that conflate leader behavior with its assumed antecedents or consequences. Moreover, the literature on relations between leadership and environmental sustainability constructs is fragmented and in need of systematic integration to effectively guide future research and practice. Accordingly, we pursue three goals in this conceptual paper. First, after a brief review of key insights from extant theoretical and empirical research, we define leadership in the context of environmental sustainability and leader green behavior based on established theoretical frameworks. Second, based on a systematic integration and extension of the literature, we present an integrative conceptual model of multilevel antecedents and consequences of leader green behavior. We further develop eight propositions on multiple known and novel pathways toward leader and follower green behaviors, as well as multiple known and novel pathways toward consequences related to environmental sustainability at the leader, follower, and organizational levels. Finally, based on our integrative conceptual model and propositions, we outline several recommendations for future research on leadership and environmental sustainability, including theoretical and methodological considerations.