SACRAMENTO, Calif.—The state Assembly narrowly approved a cap Thursday on the number of charter schools in California and banned nepotism in the hiring practices of the fast-growing alternative schools.

The bill, AB401, would limit the number of charter schools in the state to 1,450 by 2017 and impose some of the same rules that block public school employees from hiring family members.

The bill by Assemblyman Tom Ammiano, D-San Francisco, was approved 41-28 by the Assembly and now goes to the state Senate.

"Some accountability measures are needed to ensure that all charter schools are adequately performing," Ammiano said on the Assembly floor. "Charter schools are funded by public dollars" and should be