Drawing on analysis of lesson plans, observations, and interviews, the authors describe how lesson study encouraged faculty at three community colleges to implement two instructional approaches in their precollege quantitative reasoning course that differed from their usual practice and aligned with evidence on effective mathematics instruction: designing more open-ended, cognitively demanding tasks and implementing new strategies to increase mathematical communication. The authors detail the barriers faculty members encountered and the features of lesson study that ultimately facilitated their enactment. The findings suggest that lesson study may be a useful method to support the adoption of evidence-based instructional practices in developmental mathematics—and perhaps in higher education more broadly.