This article reviews research related to the construct of interaction in the educational technology and distance education literature. The review is limited to higher education and includes theories and empirical research that inform the construct of online interactions. Conceptual and operational definitions of "interaction" are categorized from three frameworks emerging from the review: interaction as an instructional exchange, interaction as computer mediated communication, and interaction as a social/psychological connection. Gaps in the research are identified and similarities that inform practice in designing and teaching in online learning environments are presented to provide linkages from research to practice. (Contains 3 tables.)