Collaboration, as one of the most essential skill sets for engineering students, remains challenging for both engineering educators and student engineers. This study explores the role of pedagogical support individual preparation before collaboration on engineering students’ collaborative learning outcome as well as the process. A total of 36 dyads engineering students from a university engineering class participated in the study, divided into 2 group formations: homogeneous group (two similarly experienced student engineers) and heterogeneous group (one experienced student engineer and one less experienced student engineer). All dyads completed two engineering design tasks in two conditions: immediate collaboration (control condition) and individual preparation before collaboration (experimental condition) in a face-to-face (F2F) computer-supported collaborative learning (CSCL) context. The results indicated the interaction effect of individual preparation and group formation on students’ collaborative knowledge co-construction. The homogeneous group formation produced higher quality knowledge co-construction and design solutions when there was an individual preparation before collaboration than immediate collaboration. Meanwhile, the heterogeneous group formation produced lower quality knowledge co-construction and design solutions when there was an individual preparation before collaboration than immediate collaboration. These findings expand the current understanding of individual preparation before collaboration and provide insights for the design of computer-supported collaborative learning in classrooms.