The authors build on literature related to the development of epistemic cognition, research on historical thinking, and studies of individuals' epistemic beliefs. They designed this study to explore, develop, and test a measure of epistemic cognition in history. They administered the Beliefs about Learning and Teaching History Questionnaire to elementary teachers and college history professors, which represents an effort to construct a reliable and valid measure that could effectively monitor changes in epistemic cognition across large samples. Results from a confirmatory factor analysis suggested a good fit of a 2-factor model underlying the questionnaire. Responses from experts in the domain of history served as an initial attempt to validate the instrument. (Contains 6 tables and 1 figure.)