The present study explores secondary school history teachers' knowledge of inquiry methods. To do so, a process model, outlining five core cognitive processes of inquiry in the history classroom, was developed based on a review of the literature. This process model was then used to analyze think-aloud protocols of 20 teachers' reasoning during an inquiry task. It was found that less than half of the teachers used all cognitive processes during the inquiry. Based on the results, a distinction can be made between an integral, fragmentary, and cursory approach to inquiry. Further analysis suggests that there exists no clear pattern in the relation between teachers' beliefs about the subject of history and their approach to inquiry. The implications for teacher training are discussed and outline how the process model could serve as an instructional tool that can contribute to a comprehensive training program for history teachers.