Museums have great potential to help secondary students develop a deep understanding of the past; however, we know little about what history teachers actually do or want to accomplish when they utilize museums. In this study, the authors draw on questionnaire and interview data from 94 secondary history teachers in Connecticut in an effort to understand teachers' objectives, practices, and dilemmas in using museums. The results indicate that while teachers value museums for their potential to promote historical understanding, a number of factors limit the quantity and quality of museum trips, including cost, logistics, and teachers' level of knowledge and skill related to museums. Many teachers view museums as authoritative and do not ask students to evaluate the way museums present the past, thus neglecting the potential of museums to promote historical thinking. In addition, teachers implement practices to prepare students for museum visits; few, however, use follow-up activities or tap museums' virtual and human resources to promote history learning in the classroom. Better professional preparation and ongoing professional development could position teachers to realize the promise of museums to promote deep--and lifelong--learning of history. (Contains 8 tables and 4 notes.)