This brief notes that very few states have developed comprehensive policies to improve and support their teaching force as they implement other education reforms. In creating a coherent system of teacher support, one important place to begin is with the state board of education, which has broad authority over teacher preparation and licensure. Systemic reform in teaching begins with the state's responsibility to ensure that all teachers not only does not harm, but also help students learn what the state has defined as necessary. A state's accountability system for teachers is one part of fulfilling the state's responsibility to help students learn. A model for a state's teacher accountability system is provided. It indicates how different mechanisms in the state's accountability system should work together to build and support a high quality teacher workforce. The brief describes how these mechanisms operate in a teacher accountability system, examining structures and processes, assessment and feedback, and safeguards and incentives. It describes performance based licensure, which requires prospective teachers to meet high standards defining the knowledge, skills, and dispositions they need to help students succeed. It notes the advantages of standards based assessment, explaining that portfolio assessment also poses challenges regarding technical quality, equity, and feasibility. (SM)