Police officers approached Peter LaBarbera and Bill Whatcott as they were handing out pamphlets on the campus Monday, telling them to leave or risk being arrested.
After some discussion, the pair refused to move and officers took them into custody.
Both were initially charged with trespassing but the charges were later changed to mischief.
LaBarbera is the head of an American lobby group that has been labelled a hate group by the South Poverty Law Center, while Whatcott has a history of legal troubles in Saskatchewan.
Both were in Weyburn, Sask., over the weekend to speak at an anti-abortion conference. They have been released with an order to appear in court on May 26.
Several human rights complaints were filed against Whatcott after he handed out anti-gay pamphlets more than a dozen years ago. The case went all the way to the Supreme Court of Canada, which found Whatcott had violated the province's human rights code and fined him $7,500.
Last week, LaBarbera was detained at the Regina airport for several hours while customs officers questioned him.