LOS ANGELES — In California public schools, students are required to learn about black history and women’s history. And if a bill approved by the State Senate this week becomes law, the state will become the first in the country to mandate that schools also teach gay history.
While the bill does not set specific requirements about what should be taught to students, it does say that contributions of gays and lesbians in the state and country must be included in social science instruction. So Harvey Milk , one of the first openly gay elected officials in the state, and Bayard Rustin, a civil rights activist, may take a prominent place in the state’s history books.
Advocates say that teaching about gay, lesbian, bisexual and transgender people in schools would prevent bullying and shatter stereotypes that some students may harbor. They point to several students who have committed suicide after being taunted by peers for being gay. But the bill has drawn vociferous criticism from opponents  who argue that when and how to talk about same-sex relationships should be left to parents.
A similar bill was approved by the Democratic-controlled Legislature in 2006, but vetoed by Gov. Arnold Schwarzenegger , who said that school curriculum should be left up to local schools. But there is a new governor now. And both supporters and opponents of the bill expect it will sail through the heavily Democratic Assembly and be signed into law by Gov. Jerry Brown , a Democrat who has been supportive of gay rights.
“It is very basic to me that people dislike and fear that with which we are less familiar,” said Mark Leno, who sponsored the bill and is one of the first openly gay men elected to the State Senate. Students who come to view their fellow classmates as regular members of society, rather than misfits, will find that “their behavior changes for the better,” Mr. Leno said.
Some school districts, including San Francisco and Los Angeles, have already put in place such a curriculum. But even in those more liberal areas, Mr. Leno said, students may not realize how recently gay, lesbian, bisexual and transgender individuals have been given more rights. For example, he said, many teenagers would be shocked to learn that it was just more than a decade ago when the state legally prohibited discrimination based on sexual orientation.
The increasing acceptance of gays and lesbians is precisely what bothers some of the opponents of the legislation. Craig De Luz, a conservative activist and school board member from Sacramento, said that in many communities “the issue of homosexuality is far from settled.”
“There is still a big cultural discussion of: Is it something that one chooses, or is it something that someone is born with,” Mr. De Luz said. “It is all part of the same agenda, which is largely about social acceptance. Now this is a way of endorsing a lifestyle that many people are morally opposed to.”
Bob Huff, a Republican from San Bernardino, said he worried that the bill would water down the state curriculum and distract students from learning the basics.
“To have something this nebulous just opens it up to problems,” Mr. Huff said. “At what age do you start doing this instruction? What is age appropriate and what is appropriate at all is really a question we haven’t answered.”
Carolyn Laub, the director of the Gay-Straight Alliance Network , who lobbied for the legislation, cited the experience of an Orange County student as an example of how the law might work. When the student learned that the civil rights protests of the 1960s would be discussed in history class, he asked the teacher to talk about the Stonewall riots .
“Suddenly students see he is part of a broader community, and they have a much better understanding of that community in the context of the rest of the world,” Ms. Laub said. “It has absolutely nothing to do with sex; it’s about entire communities that are left out.”