Historical sources are a common feature of history classrooms, but the purpose of using them is not always clear, and as a result, instructional activities with sources may not be as effective or meaningful as they should be. This lack of clarity stems in part from the fact that there are four distinctly different reasons for using sources, and each carries its own implications for classroom practice. These purposes are 1) illustration and motivation; 2) evidence for historical inquiry; 3) visual or textual interpretation; 4) source analysis. By reflecting on how each of these purposes can play a role in the classroom, which kinds of sources are appropriate for each, and where they fit into an overall sequence of instruction, teachers can ensure that their use of sources deepens and extends students’ historical understanding.