Online courses are now a significant part of the higher education landscape. Faculty awareness of the needs of the changing population served, the inherent challenges in learning online, and the importance of enhancing student engagement are of paramount importance to successful online course design. Knowledge of theory and research in adult learning and student engagement, as well as Communities of Inquiry, provide a foundation for understanding teaching and learning in this context. This foundational knowledge has been synthesized in this article into a framework of critical components for engagement of adult online learners that can be used to inform development of online course assignments and activities that maximize student engagement and learning. A tool for embedding the critical components for student engagement is provided to support instructors' development of online courses.