Online collaboration has led to surprising successes like Wikipedia, YouTube, open-source software, and more. Yet we are still in the early days of understanding its potential, and how to deliberately engineer systems to make new things possible. Both tools and social context for collaboration shape what is possible. In this talk, I’ll present research at Georgia Tech on creating new  collaborative systems and deploying them with real users.  Further, I'll share empirical results on the context for collaboration, particularly how users' (mis)understandings of copyright law affect their online behavior.