The implementation process of teacher evaluation policy is often problematic. In this regard, it is crucial to understand principals’ sensemaking of teacher evaluation policy since their understandings influence the implementation process. While a growing body of research shows that principals strongly shape teachers’ policy understanding, little is known about the way principals’ sensemaking is influenced by teacher expectations about new policy. This qualitative study, drawn from interviews with principals and teachers in 13 secondary schools, indicates that the new teacher evaluation policy in Flanders (Belgium) is implemented by principals and supported by teachers in various ways. The findings of this study show this was the result of the process of discrepancy reduction between the initial standards principal set and the expectations that teachers had for the implementation of the policy. These findings underscore the complexity of teacher evaluation and help policy makers to understand that “the best” implementation of the teacher evaluation policy probably does not exists. Moreover, this offers important insights for principals in how they best lead the implementation of teacher evaluation.