Design projects are one form of project-based learning whereby students propose, build, and test an artifact to meet a specific need. This paper presents the design, implementation, and evaluation of a computer-based tool ("Co-Net") designed to support students in the process of working on design projects (in this case, instructional design projects). "Co-Net" was implemented over two successive semesters, with approximately 43 students using it. Based on the classroom trials reported here, one major finding was that providing access to others' published artifacts through the Web is a simple but powerful strategy to help learners to elaborate initial ideas, prompt reflection and evaluation of their own designs, and promote engagement in the larger design community. Also, facilitating the exchange of online feedback about one's project design was perceived to be useful, but only when feedback was substantive, offered suggestions, or pointed out limitations in the design.