In 2009-10, NAPCS collected data to determine the teachers’ union status of every charter school nationwide. NAPCS defined a charter school as unionized if it had a collective bargaining agreement with a teachers’ union or association. There were additional charter schools without collective bargaining agreements that hired teachers who were members of a teachers’ union. These schools were not counted as being unionized.
NAPCS collected union data by contacting a variety of sources within each state. The sources included state departments of education, charter school support organizations and resource centers, charter school authorizers, national union organizations, and local affiliates of the national union organizations.