This study investigated EFL college-level learners’ expectation on and their experience in an online English-medium instruction (EMI) course focusing on how participants interacted with their classmates and the instructor in their online class (zoom session) based on assumptions and rationales of Interaction Hypothesis and classroom interaction research. Analyses of questionnaire, observation, and interview data revealed that participants’ experience of interaction and their perception of interaction opportunities in the zoom session were significantly related to how they would evaluate the course-taking experience. It was also found that cognitive strategy such as participants’ preparation for each class rather than L2 confidence was more relevant to their level of satisfaction with the course. Results of analyses suggested that an online class could be more effective than a face-to-face class in terms of engaging EFL adult learners in an academic course offered in participants’ L2, English. Based on study results, suggestions on how to increase interaction opportunities in online EMI course are made.