Case studies are frequently used to prepare preservice teachers through reflection and analysis of classroom situations. Previous research suggests asynchronous online discussions provide more opportunity for reflection and analysis than face to face environments. Online case study discussions of two groups of preservice teacher education students, one more and one less successful, were analyzed through a case study approach with a cross-case comparison. Discussion transcripts were analyzed and triangulated with student self-report data. Members of both groups participated relatively equally and adopted a cooperative approach to the task. The more successful group exchanged more messages and responded to each other. Both groups focused on the task and content, but the more successful group also socialized and engaged in supportive discourse. The more successful group also supported their claims. Neither group challenged each other's initial ideas, nor did they ask many questions. As a result, the opportunity to create meaning together was not fully explored. Findings may be attributed in part to a difference in attitude toward the task itself and the idea of group work in general. Recommendations for the design of online case studies are discussed. (Contains 10 tables.)