Some 18,000 students, teachers and other guests are expected at the event, which is meant to inspire youth to create change in their communities and around the world.
WCCO-TV reports that performers at the event include Demi Lovato, Carly Rae Jepsen and the Jonas Brothers; and that Martin Luther King III, Queen Noor of Jordan and actress Mia Farrow are among the speakers.
Among the local politicians attending the event are Gov. Mark Dayton and St. Paul Mayor Chris Coleman.
The station says tickets couldn't be bought to attend We Day Minnesota. Instead, students had to earn their way through volunteerism.
St. Paul is hosting the second We Day in the nation, following a successful event in Seattle.
Streets near Xcel will be closed or reduced to one lane until 9 a.m. Tuesday morning, and again this afternoon from 1:30 to 4 p.m. because of the event.