Aninmated short "Lava" will be shown before "Inside Out" when Pixar's story of a big family move arrives in cinemas in June 2015.
Taking place over millions of years, "Lava" will be a love story with musical themes, set against a backdrop of volcanic tropical islands.
James Ford Murphy, who has worked on a host of Pixar films including "Toy Story 2," "Cars," "The Incredibles" and "Ratatouille," will direct.
He was also involved in the seven-minute "Mater and the Ghostlight," which was part of the DVD home release of "Cars," and three-minute "For the Birds," which accompanied the "Monsters Inc." package at retail and then as a 3D theatrical re-release.
"Inside Out" stars Amy Poehler, Bill Hader, Lewis Black, Mindy Kaling and Phyllis Smith as a quintet of emotional impulses that try to guide a young girl, Riley, through the experience of moving from the rural American Midwest to bustling San Francisco.
Its June 19 US release date lands it in the same week as the new "Fantastic Four" film, two weeks after DreamWorks Animation comedy "B.O.O.," three after Paramount Animation's "Monster Trucks" and three before Universal's "Despicable Me" spin-off "Minions."