In this article we share the Academic Communities of Engagement (ACE) framework, which describes a student's ability to engage affectively, behaviorally, and cognitively in an online or blended course independently and with support. Based on Vygotsky's (Mind in society: the development of higher psychological processes, Harvard University Press, Cambridge, 1978) zone of proximal development, the framework examines how a student's ability to engage in online or blended courses increases with support from two types of communities. The course community is organized and facilitated by those associated with the course or program. The personal community is comprised of actors not officially associated with the course who have typically formed relationships with the student before the course or program began and may extend well beyond its boundaries. Actors within each community have varying skills and abilities to support student engagement, and a student is most likely to reach the necessary engagement for academic success with active support from both. The framework identifies the community actors most likely to provide specific support elements, aligning them to the different types of student engagement. The article outlines implications for practice and research, concluding with illustrative examples.