What is--or should be--the purpose of a teacher evaluation system? To compare teachers? To inform the public? To help teachers improve? Legislators might say that a teacher evaluation system's purpose is to remove bad teachers. Administrators might say that it is to assist them in matching teacher skills to specific groups of students. Parents might say that it is to provide information about a particular course. Teachers might say that it is to increase their effectiveness in the classroom. As states and school districts experience the growing pains of changing their evaluation systems, determining the purpose of the teacher evaluation system is essential. When the authors started their positions as peer reviewers in Miami-Dade County Public Schools, they decided to explore this idea. While some legislators and administrators might say that an evaluation system's purpose is to measure teacher competence, they disagree. To illustrate, they present Miami-Dade County Public Schools' Instructional Performance Evaluation and Growth System, which is an example of a teacher evaluation system that integrates professional learning.