In this article we argue that interactive writing (IW), an approach to writing instruction, is uniquely supportive of secondary content-area teachers working to integrate meaningful writing instruction without sacrificing time or attention to content. Drawing on research and our experiences with IW in middle school settings, we explain the roots of IW and its potential to support powerful writing instruction in the disciplines because of its emphasis on externalizing thought, negotiating meaning, and teaching conventions of writing and language in the context of real writing.