Abstract. Online discussion plays a unique role in face-to-face and distance teaching and learning. Interaction and student cognitive engagement during the online discussion are critical for constructing new understanding and knowledge. This article analyzes types of interaction that occur during online discussions, examines levels of student cognitive engagement in each discussion, and explores their effects on and implications for learning and teaching in higher education. By combining methods of social network analysis with qualitative content analysis, the article explores new methodologies for analyzing participation, interaction, and learning that take place online, and suggests areas for research in learning and teaching online.Keywords: asynchronous discussion, cognitive engagement, computer-mediated communication, discussion forum, electronic conferencing, interaction, teaching and learning online Advances in technology have enhanced communications between students and the instructor, and among students themselves. Many college instructors, due to easy access to communication technology tools, have moved or extended part of a classroom discussion to an online forum, where students and the instructor continue their discussion on course-related topics. Instructors sometimes find it difficult to facilitate class discussions online because there remains scant knowledge about interaction and student cognitive engagement in the asynchronous online discussion. This article analyzes types of interaction in four asynchronous online discussions, examines student cognitive engagement in each discussion, explores factors that may cause differences in interaction and cognitive engagement, and highlights possible implications for learning and teaching online and for research in computer-mediated communication (CMC).