Due to its focus in project-based learning, design educators must provide individual coaching and mentoring of student teams as they progress through their design efforts. In order to increase the quantity and quality of design mentoring, the authors have implemented the use of Wiki websites as a medium for providing formative assessment for student design teams enrolled in a sophomore-level Mechanical Engineering design course. Wiki websites, which allow for easy creation and editing of interlinked webpages, were created for each design team in order to provide a virtual space for the creation, compilation, and editing of their design project report submissions. With access to each team's Wiki site, the mentor is able to observe each team's product design process unfold and provide feedback using an embedded commenting system. The public presentation of design reports also affords the facilitation of a peer-review of student work. In this paper the authors present details of the implementation of a Wiki for preliminary assessment data for this tool. Results show that the students found the tool and the associated activities to be easy to use, helpful in developing better design reports and a contributing factor to their development of critical and analytical thinking skills. In addition, students who used the tool reported receiving more meaningful formative feedback from the instructor and reported giving more formative feedback to their peers when compared to other sections of the class that were not using the Wiki.