This research explored how between-group collaboration enhanced the co-construction of knowledge and performance on project-based learning tasks of collaborative learning groups. The findings of 2 case studies, one that focused on between-group mentoring and one that focused on between-group project review, revealed that both strategies were perceived favorably by the students and had a positive impact on the collaborative learning skills, the knowledge revealed through their online dialogue, and the project performance of all students, especially the less effective groups. The results provide some insights into the computer-supported collaborative learning process among students in a higher education context.