Students, staff and visitors will be cleared to bring concealed guns onto Idaho's college and university campuses.
Gov. C.L. "Butch" Otter signed the bill into law Wednesday.
It allows retired law enforcement and concealed-carry permit holders bring guns into classrooms and anywhere else on campus - except dormitories and stadiums.
The proposal drew heated criticism from heads of all eight of the state's public colleges and sparked a protest that drew hundreds to the Capitol.
Opponents say it will strip policy-making power from universities, stymie recruitment efforts and put those on campus at risk.
Otter wrote in a statement he backed the bill to protect Second Amendment rights.
He says Idaho will carefully monitor the situation to alleviate public safety concerns.
The new law goes into effect July 1.