After she was released, LeFavour said she was treated respectfully by law enforcement.
"We have no issue with police," she said. "Our issue is with a Legislature that won't stand up and say 'cruelty to gay, lesbian and transgender people is wrong.'"
The issue of gay rights has become prominent in Idaho.
In a pending federal case, four couples have sued to overturn Idaho's 8-year-old ban on gay marriage.
A Republican lawmaker introduced a bill last month to forbid the state from revoking professional licenses of those who refuse service or employment on religious grounds, triggering opposition from gay rights' supporters and civil liberties groups.
And last year, tax commissioners barred same-sex couples legally married in other states from filing joint Idaho income tax returns.
The arrests Monday began after Senate President Pro Tem Brent Hill attempted to enter the chamber about 11 a.m. but was blocked. About a half hour earlier, organizers had sent notice to media outlets saying arrests were imminent.
"We respect your right to protest, but we also have the right to do the job people elected us to do," he told protesters before police intervened, adding it was "irresponsible" of them to block the hearing room.
"Those are the chambers, and they belong to all the people, not just this group," he said.
The demonstrators wore black-and-white "Add the Words Idaho" T-shirts and covered their mouths with their hands, a symbolic gesture intended to call attention to a bill that would add four words sexual orientation and gender identity to Idaho law banning discrimination in employment, housing and business services.
Hill, R-Rexburg, and other Idaho Republicans have blocked passage of such a proposal for eight years, and they have declined to give a hearing to such a plan this year.
Protesters, who ranged from high school age to their 70s, said they wanted to make a point.
Meredith Butts, an 18-year-old Boise High School student, said she got involved after seeing her friends face discrimination for their sexual orientation.
"I want people who are my age and people who are younger really, anyone to not have to hide who they are to prevent harm to themselves," she said, adding that the prospect of arrest hadn't deterred her.
Ty Carson, 41, a Boise resident, was among those arrested. Carson complained of verbal harassment in bathrooms, locker rooms and restaurants.
"That sort of discrimination should not happen to any of Idaho's citizens," Carson said. "Until the Legislature says it's wrong, the message they're sending is that it's OK."
Carson and other protesters had been escorted to the front door by a state trooper and told they could re-enter, provided they didn't cause a repeat disturbance.
They now face misdemeanor trespassing charges, punishable by up to six months in jail and a $1,000 fine.
Amid growing tension over whether an "Add the Words" bill will get a hearing, Idaho's Capitol has been the scene of several low-key protests. On Friday, for instance, a small group with guitars sang songs in the Capitol, urging lawmakers to take up the issue.
LeFavour predicted additional action if lawmakers don't agree to hold a hearing, saying "I don't think you could stop people from showing up in greater numbers to do something peacefully, but pointedly, again and again and again."
Associated Press writer Katie Terhune contributed to this report.