A teachers’ union is a labor union (an organized group of employees) that represents teachers or educators in contract negotiations (for salaries, tenure, paid time off, and other terms of employment) with schools or school districts. Teachers’ unions are said to engage in collective bargaining—bargaining or negotiating on behalf of all teachers—rather than individual teachers negotiating their own employment terms.

The rights of workers to form unions, strike, bargain collectively, and engage in other work-related activities are provided by the federal statute known as the National Labor Relations Act of 1935 (NLRA). The NLRA also prohibits unions from trying to force workers to join a union and prohibits employers from retaliating against workers who exercise their union rights.

The NLRA supersedes many state laws but it does not apply to employees in the public sector—including public school teachers. Some states have laws that prohibit collective bargaining for public employees (Georgia, North Carolina, South Carolina, Texas, Virginia) and many states have laws that make it illegal for public employees to strike.

In New York, teachers' unions are recognized entities that represent educators in collective bargaining with school districts. These unions negotiate on behalf of teachers for various employment terms such as salaries, benefits, and working conditions. While the National Labor Relations Act (NLRA) of 1935 establishes the right to form unions and engage in collective bargaining for private-sector employees, it does not apply to public-sector employees, including public school teachers. However, New York State allows public-sector employees, including teachers, to form unions and engage in collective bargaining. New York State's Taylor Law specifically grants public employees the right to organize and collectively bargain while also prohibiting strikes. The Public Employment Relations Board (PERB) administers this law. It's important to note that while New York supports collective bargaining for public school teachers, it also imposes certain restrictions, such as the prohibition of strikes, to maintain public services.