Background/Context: Teachers' values and beliefs shape how they make professional decisions. In particular, they shape teachers' decision-making in the face of ethical dilemmas, including dilemmas about grading, promotion, and student support. However, very few studies in teacher professional development (PD) have explored teachers' values-based decision-making in context and how to support values-based decision-making through professional learning. Focus of Study: This article analyzes data from a PD on ethical decision-making in education that gave 149 educators the time, space, and scaffolding to reflect on and discuss the values at the core of their practice and how those values shape their approach to ethical dilemmas in education. Research Design: This study is based on data collected during a PD offered by the Chicago Public Schools Office of Social Science and Civic Engagement. A total of 149 teachers independently completed an online simulation version of a normative case study--a vividly detailed case study of an ethical dilemma of grading and promotion in education--then discussed the case in small, facilitated groupings. This article analyzes presurvey, journal entry, and discussion transcript data at three time points during the PD to describe how educators' articulation of values changed over the course of the experience. Conclusions/Recommendations: Analysis suggests that the PD supported teachers in developing their willingness to discuss their values with their colleagues, a realization that values connect to larger systems and structures in education, and an understanding that values are interpretable based on context. Based on this analysis, this article recommends values-based PD for in-service educators as a key component to establishing schoolwide systems that can guide educator decision-making in the face of ethical dilemmas. It suggests that normative case studies in educational ethics are a promising practice for such PD.