The National Center for Education Statistics (NCES) sponsors the National Teacher and Principal Survey (NTPS) on behalf of the U.S. Department of Education in order to collect data on public and private schools, principals, and teachers in the United States. The U.S. Census Bureau conducts the survey for NCES. The NTPS provides data on the characteristics and qualifications of teachers and principals, teacher hiring practices, professional development, class size, and other conditions in schools across the nation. The NTPS is a large-scale, nationally representative sample survey of K-12 public and private schools and the principals/administrators and teachers who staff them in the United States. The NTPS replaced the Schools and Staffing Survey (SASS) in 2015, which had historically collected the information necessary to form a complete picture of elementary and secondary education in the United States. The NTPS has a different structure and sample from previous administrations of the SASS; however, it maintains the same focus on schools and their teachers and administrators that was traditionally held by the SASS. Like the SASS, the NTPS provides a wide range of opportunities for analysis and reporting on elementary and secondary educational issues. The 2020-21 NTPS data products include six restricted-use data files: Public School, Public School Principal, Public School Teacher, Private School, Private School Principal, and Private School Teacher. This Documentation report provides information about all phases of the NTPS, from survey questionnaire revisions to survey data collection and all phases of data processing.