Based extensive fieldwork and interviews, this study explains teacher evaluation policy enactment as shaped by three conditions: (1) a principal's backgrounds, role perceptions, knowledge of instruction, and interactions with teachers; (2) teachers' perspectives; and (3) environmental demands. Notably, principals may lack the backgrounds, knowledge of teaching, role perceptions, and established interactional routines to engage teachers about their instruction in evaluative contexts. Furthermore, the teachers' press to earn high evaluation scores may inhibit instructional leadership, as teachers become focused on the accountability aspects of evaluation rather than on the affordances of evaluation reforms to help them improve.