This case study, based on social constructivist learning theory, investigated the communication patterns and the knowledge construction process of students who used a computer bulletin board system (BBS) to discuss course-related content. Collected data included the outline of BBS postings and transcripts of the BBS messages from three selected weeks during the semester in an advanced communications class. Quantitative analysis was used to examine participation and interaction rates, and qualitative procedures were used to analyze knowledge construction processes and to refine a category system of indicators and descriptors. Results showed that students engaged in a knowledge construction process that was characterized chiefly by clarification, elaboration, and interpretation, and that produced more reflective monologues than dialogical interactions. Findings were related to constructivist theories and to previous analyses of computer conferencing systems, and were used to develop a list of recommendations for practitioners interested in incorporating such systems in their courses.