The bill, SB179, makes California the first state in the country to offer the nonbinary option for people who want their documents to match their gender identity. While most recent bills that Brown, a Democrat, signed will go into effect January 1, 2018, this bill will take effect a year later.
"Nonbinary" is the umbrella term for people who do not consider themselves either female or male.
The law also will allow people to be able to change their gender identity on their birth certificates.
In July, Oregon became the first state to allow people to mark their gender as "not specified" on driver's licenses and identity cards. Instead of a M or F for male or female, Oregon's licenses have an X.
"I want to thank Governor Brown for recognizing how difficult it can be for our transgender, nonbinary and intersex family members, friends and neighbors when they don't have an ID that matches their gender presentation," Democratic state Sen. Toni Atkins, who helped author the bill, said in a statement. "I have dear friends in San Diego and around the state who have been waiting a long time for this."
Not everyone in the state supported the bill. The conservative California Family Council opposed it, telling SFGate that the legislation "advances a lie; that being male or female, or no gender at all, is a choice each person has a right to make."