Historicalthinkingmatters.org, a collaboration between the Center for History and New Media at George Mason University, pioneers of online historical resources, and Stanford University's History Education group, a research center that investigates the teaching and learning of history, addresses the problem of an abundance of historical texts and a dearth of students able to read them with sophistication. The project uses web-based resources for teachers and students designed to democratize historical understanding and to develop core features of academic literacy. Materials focus on teaching students how to read historical documents critically and how to synthesize textual evidence into coherent narratives. This article introduces the project and the three major sections that provide access to digital materials: (1) an introduction to the site's approach; (2) teacher materials and strategies; and (3) student investigations. Teacher sites for each unit include resources to help teachers plan and teach document-based historical reasoning using the materials available on the corresponding student site. Two components, video think-alouds and audio commentaries, work together to make historical reading processes visible and explicit for the student. The questions that students answer for each document also serve this purpose. Each question is identified as a sourcing, contextualizing, corroborating, or close reading question. The consistency of this frame and the multiple examples of each kind of question give students practice with ways of reading that may initially seem strange. The hope of the developers is that every American history teacher can find something of use on the site, whether it be a week-long lesson, a single document, or several ideas about how to introduce students to interrogating sources, serving as a resource for ways of thinking about history instruction and learning more about historical reading and thinking. (Contains 4 figures and 6 notes.)