The American Federation of Teachers says teachers at Detroit's Cesar Chavez Academy have voted to unionize the charter school.
The union said Thursday that teachers, counselors and social workers voted 88-39 to make the AFT their bargaining agent.
They will be represented by the Michigan Alliance of Charter Teachers & Staff, an AFT local.
The school is run by the Phoenix-based Leona Group, which operates in Arizona, Florida, Indiana, Michigan and Ohio. The Associated Press left phone and email messages for the company after business hours Thursday.
No one answered the school's phone Thursday night.