Engaging historiography and interpreting secondary sources represent essential elements of historians' work that have been largely ignored in favor of primary source reading in high school history classrooms in the United States. To understand whether and how students apply their historical reasoning skills to secondary sources, we asked twenty-four high school sophomores to think aloud about a historiographic problem. Students were divided into three conditions receiving either the historiographical documents without scaffolding, the documents with explicit written framing, or the documents with explicit written framing and oral instruction. We found that all students sourced, corroborated, and contextualized, but students who received explicit framing with dialogic instruction were significantly more likely to engage in complex evidence evaluation than students in the other two conditions. The results suggest that fuller models of historians' disciplinary practices may be needed in history education.