MUNCIE, Ind. — Six months into retirement, David Letterman stepped onstage here at Ball State University looking much the way he did as host of “Late Show”: suit and tie, loafers and white socks. But he has grown the kind of beard a man wears when he doesn’t have to get up for work every morning — looking not so much like Santa Claus but, as he said, like Charles Darwin.

In his first visit to Ball State, his alma mater, since retiring after 33 years in late-night television, Mr. Letterman moderated a conversation with the movie directors Spike Jonze and Bennett Miller that touched on everything from filmmaking mistakes to sexism in Hollywood.

After the Top 10 lists and the 16 Emmys, the on-camera breakups (Crispin Glover) and makeups (Oprah Winfrey), Mr. Letterman, 68, can always come back to Ball State, where he started his career in broadcasting at the campus radio station. And he has come back, many times, bringing with him the likes of Rachel Maddow and Ms. Winfrey as part of a lecture series he financed.

On Monday night, the university president, Paul W. Ferguson, announced that Mr. Letterman would donate all of his Emmys, part of his “Late Show” set and other memorabilia to his alma mater. Ball State will call the exhibition “The David Letterman Experience,” a title that prompted some self-effacing mockery: “If you can call sitting behind a desk and pretending to talk to actors an ‘experience,’” Mr. Letterman told the audience of more than 3,500 at the university’s Emens Auditorium.