The quality of a teacher's instruction is widely understood to be the most important school-based factor in student learning. By taking positive steps to retain their strongest teachers, principals can maximize the impact of teacher retention on instructional quality, a process referred to as "selective retention." This brief from the Reform Support Network explores promising State and district approaches for incorporating teacher retention standards into principal evaluation frameworks. The brief also examines five key decision points for future implementers to take into account if considering this measure in their principal evaluation systems.