Monsters, Inc. was Pixar’s fourth feature film when it was released.
Pixar’s first four theatrical features were Toy Story in 1995, A Bug’s Life in 1998, Toy Story 2 in 1999, and Monsters, Inc. in 2001. Counting those releases places the monster comedy fourth in the studio’s feature-film chronology.
This numbering is about Pixar’s released feature films, not the order in which the studio developed ideas or produced short films. Pixar had made many shorts before its first feature, including the Oscar-winning Tin Toy, but those are not included in the feature count.
The number is also easy to confuse with Monsters University’s position in Pixar’s filmography. The prequel arrived much later, in 2013, after many additional Pixar features including Finding Nemo, The Incredibles, and WALL-E.