Across the nation, states and districts are in the process of building better teacher evaluation systems that not only identify highly effective teachers but also systematically provide data and feedback that can be used to improve teacher practice. "A Practical Guide to Designing Comprehensive Teacher Evaluation Systems" is a tool designed to assist states and districts in constructing high-quality teacher evaluation systems in an effort to improve teaching and learning. This tool is not a step-by-step guide to devising a teacher evaluation system. Rather, it is intended to facilitate discussion and promote coherence in the development process. The guide begins with an overview of the factors influencing teacher evaluation reform today and continues with a discussion of approaches to balancing state accountability and district autonomy. The next section of the guide is structured around the following essential components of the design process as supported through research: