To teach in a web-based environment, what should the new instructor know about online interaction? This paper first reviews four instruments that examined the processes and outcomes of interaction (the foci are more on the interaction behaviors) and three instruments that examined interaction from a structural view (the foci are more on the interaction patterns). This paper then continues with the discussion on how to involve interaction theories in web-based learning. The author intends to explore the questions: What tools are currently available to facilitate the design and delivery of interaction in online learning? What factors have shown salient influences on group interaction? And how can the educators, instructional designers, and researchers utilize those research results? The purpose of the paper is to present the variety of options and the basic principles for designing and implementing interaction for new online instructors.