The Halloweentown movies should be watched in the following order:

1. Halloweentown (1998)
2. Halloweentown II: Kalabars Revenge (2001)
3. Halloweentown High (2004)
4. Return to Halloweentown (2006)

All four movies are part of the same series and were released as Disney Channel Original Movies). The first movie introduces the main characters and sets the stage for the rest of the series. The second movie picks up two years after the events of the first film, and the third movie is set two years after the events of the second film and moves the setting from Halloweentown at large to high school. The fourth and final movie features a new actress playing the main character, Marnie Piper, and takes place several years after the events of the previous movie).