In 2009, the United States Department of Education (USDOE) incentivised states to create more rigorous teacher evaluation systems that better differentiated teacher performance as well as provided more information on what makes a high-quality teacher. One result of these revised teacher evaluation systems was principals, in most cases the primary evaluator of teacher performance, were tasked with collecting new and/or different data on teacher performance. However, little research investigates teachers' perceptions of how their evaluator carries out this important work. To investigate this phenomenon I asked: (1) What are teachers' perceptions of how their school principal uses a new teacher evaluation system?; and (2) In what way(s) do these perceptions influence teacher engagement in the evaluation process? Data come from K-8 grade public school teachers in the U.S. state of Michigan and includes interviews with teachers and observations of teachers during their official teacher evaluation process. Findings show teachers generally believe their principals are using new evaluation systems in ways that are beneficial to their growth as educators, which leads to teacher engagement in the evaluation process.