This Data Point compares the sources of information in evaluating teacher performance and how the information is used by traditional public school and public charter school principals in the United States. It uses data from the public school principal questionnaire from the 2017-18 National Teacher and Principal Survey (NTPS), a nationally representative sample survey of public and private K-12 schools, principals, and teachers in the 50 states and the District of Columbia. State representative information is also available for public schools, principals, and teachers.