Many researchers in the social studies have supported the use of primary sources in history classrooms as a support for historical inquiry. Although primary sources have become accessible via the Internet, simply using digital primary sources, does not automatically translate into historical thinking or technology best practice. Consequently, an evaluation matrix was constructed for one study to gauge the fidelity of primary source use according to three domains, curriculum content, instructional processes, and student products or outcomes. In this article, the researchers provide background information on the development of the evaluation matrix, present the instrument, and evaluate its effectiveness in categorizing both primary source and technology usage.