Software projects are inherently cooperative, requiring many software engineers to coordinate their efforts to produce a working software system. A firm understanding of cooperative processes is hence essential to understanding software development, and efforts to improve project efficiency. This talk presents a view of software engineering collaboration where the key activity is the resolution of conflicting or ambiguous views of the system under construction. Shared understanding is captured in a series of project artifacts (source code, design documents, requirements, test plans, etc.) which, in turn, leads to a model-based focus for software engineering collaboration tools. The talk presents several proposals for future directions in collaborative software engineering. These include shifting IDEs to the Web, integration of social networking sites, broadening participation in design, and capturing design rationale. A unifying theme across these future directions is how they increase project awareness and reduce barriers to communication, thereby opening more opportunities to detect and mediate differing mental conceptions of the software system under construction.