This embedded mixed-method study used surveys, interviews, and website analytics to understand the experiences of open educational resource (OER) authors and adopting instructors as they used the EdTech Books (ETB) open publishing platform. Participants reported various motivations for using ETB, namely reducing student costs, a commitment to openness, a vision of an OER community, and the platform’s improving usability. They also indicated that the process demanded more resources than institutions provided and identified several unique and unexpected challenges to OER work. These findings are expected to be useful for developers and administrators of OER authoring platforms as well as potential OER authors, their institutions, and instructional support personnel by helping to identify challenges and potential solutions within such efforts.