The Community College Open Textbook Project (CCOTP) was developed to support the use of textbooks that are freely available and accessible online, and that can be adapted by teachers and learners to meet their unique needs and contexts. This article presents the findings of a research study conducted by the Institute for the Study of Knowledge Management of Education (ISKME) on CCOTP. The study examined the adoption and use patterns of teachers and learners as end users of open textbooks, finding that important initial drivers of use included reduced cost, dependable quality and ease of use, and that teachers and learners use open textbooks in ways that reflect their existing teaching and learning practices. The study also showed the potential for new teaching and learning behaviours aligned to the use of open textbooks, including increased teacher collaboration on curriculum development and the interactivity of open materials as an enhancement of student learning. In addition, the study identified challenges for the sustainability of the open textbook model, including teacher technological efficacy and professional development that supports open textbook use.