Many online learning experiences integrate some form of dialogic interaction among instructors and learners. However, the degree to which these individuals come to a mutual understanding of their task and topic, a phenomenon called intersubjectivity, often remains a question. This systematic review of online learning research examines 48 peer-reviewed journal articles published between 2004 and 2021, looking at the overall trajectory of the research conversation across time, disciplines, modality and learning activities; major trends in methods, and focus; and interconnectedness. Findings suggest a dispersed body of literature, with some small groups of interconnected work but little cohesion or traction as a research field. This review has implications for future researchers in this area, who are encouraged to synthesize across this body of research and work together to establish and pursue an agenda for the field that will not only further inquiry in this area but also lead to practical knowledge about learning activity design and facilitation that is useful to online instructors.