This study examined a state-wide, policy-directed teacher evaluation model implemented across public schools and educator preparation programs. Such models are grounded in a theory of action that situates teacher learning within social relationships, yet does not account for the complexity of systems. Results challenge policy's implicit theory that an evaluation model can function as a boundary object to create a common understanding of good teaching and positively impact teacher professional practice. We found contradictory evidence that the model served as a boundary object that facilitated shared sensemaking as mediated understandings of good teaching collided with expectations in classroom contexts.