Hillary ClintonHillary Rodham ClintonTrump aide: 'Hillary is the one who’s got a gender gap' WaPo editorial board: 'No excuse' for Clinton email practices Overnight Finance: Puerto Rico bill clears panel | IRS chief vows to finish term | Bill would require nominees to release tax returns MORE will speak at the McCain Institute's annual Sedona Forum on Saturday with Sen. John McCainJohn McCainOvernight Finance: Puerto Rico bill clears panel | IRS chief vows to finish term | Bill would require nominees to release tax returns Overnight Defense: Pentagon chief fears sequestration's return Groups urge Senate to oppose defense language on for-profit colleges MORE (R-Ariz.), the institute announced Thursday.
In a statement, McCain said he is "very pleased" his "friend" Clinton could join this year's forum.
Both served in the Senate together when Clinton represented New York from 2001 until 2009. She lost the 2008 Democratic primary to President Obama, and he appointed her to be his first secretary of State.
Clinton is now being closely watched to see whether she moves the needle on a potential 2016 presidential bid.
This year's forum focuses on "Crisis in the Middle East: Values, Strategy and Options." Sessions will also cover issues regarding Ukraine and Russia, and combating human trafficking.
Other lawmakers attending the event include Sens. Kelly Ayotte (R-N.H.), Bob Corker (R-Tenn.), Heidi Heitkamp (D-N.D.), Angus King (I-Maine), Amy Klobuchar (D-Minn.) and Sheldon Whitehouse (D-R.I.).
U.S. Deputy Secretary of State Ambassador William Burns, who's retiring later this year, will also attend.
The institute said business leaders, philanthropists, activists and experts on solutions to "real-world problems" will participate in the forum as well.
Last year's Sedona Forum featured remarks from Vice President Biden and six heads of state, among others.