Several schools, districts, and individual teachers across the country are expected to promote Lesbian Gay Bisexual Transgender History Month to students during October.
But the Pacific Justice Institute is issuing a warning to parents, saying gay history in school is inappropriate.
The group points to the main website for LGBT history month, which highlights "historical figures" in the LGBT movement.
Among the usual activists and celebrities are individuals whose work is X-rated, including a man known for his contribution to gay porn and a bisexual erotic fiction author.
"It is deeply disturbing that the organizers of LGBT History Month think our kids should be celebrating homoerotic authors and porn producers," Brad Dacus, president of Pacific Justice Institute, said.
"This should be a serious wake-up call for anyone who still thinks gay history in schools is a good idea," he warned.
PJI Staff Attorney Matthew McReynolds added, "This is exactly why we fought California's gay history mandate a couple of years ago."
"We knew this was not about real history," he continued. "It was about pushing a political agenda and sexualizing kids at increasingly young ages. It is completely irresponsible for the organizers of this event to promote individuals whose work is utterly inappropriate for minors."