''Superstar'' is about a girl named Mary Katherine Gallagher, who dreams of being kissed, and decides the only way this can happen is to become a star. She daydreams all the time, so she is moved to the special education class at St. Monica High School, the Catholic school she attends.

A Catholic magazine is hosting a talent show -- the Let's Fight Venereal Disease Talent Contest -- at her school, and first prize is a role in a movie with good morals. Mary Katherine sees that her big chance is the talent show, and strives toward that. However, her grandmother will not let her enter the contest. Mary Catherine's competition is head cheerleader Evian, who is dancing with the jock Sky, the object of Mary Katherine's affections.

When Grandma Gallagher finds out that Mary Katherine went behind her back and enrolled in the talent show anyway, she tells Mary Katherine the truth about how her parents died: They were stomped to death in an Irish step dancing competition.

Despite this, Grandma Gallagher decides to help her win the talent show, and Sky's heart. However, another classmate, Slater, is after Mary Katherine's heart.

!! This movie provides examples of:
* AccidentalMurder: How Mary Katherine's parents died.
* AllGuysWantCheerleaders
* AlphaBitch: Evian
* AttentionDeficitOohShiny: Mary Katherine and Helen
* BigManOnCampus: Skye
* BilingualBonus: The story takes place in the town of Besame which means "Kiss me" in Spanish.
* BlackComedy: Mostly the parts which refer to how Mary Katherine's parents died. Also when [[spoiler: Slater]] mentions how his parents died.
* BucketBoobyTrap: at the audition for the talent show. Filled with paint, not [[ShoutOut pigs']] [[{{Carrie}} blood]].
* CatholicSchoolGirlsRule
* TheCheerleader: Evian
* ChristianityIsCatholic
* {{Cloudcuckoolander}}: Mary Katherine and her friends.
* DawsonCasting: Molly Shannon was in her mid thirties while being surrounded by age appropriate looking extras and actors, standing out completely.
* DeceasedParentsAreTheBest
* DivineIntervention: Slater turns around when Jesus intervenes.
* DoggedNiceGuy: Slater
* DrugsAreBad: Played with when Father calls role in class:
-->'''Father:''' Thomas Smith?\\
'''Thomas:''' Here! But I don't know where here is man, 'cause I'm so wasted man!\\
'''Father:''' Thomas, it is a sin to even pretend that you-you-you're baked.
* ExtravertedNerd: Mary Katherine.
* GreenEyedMonster: Evian, when she's dumped.
* HeartwarmingOrphan: Mary Katherine [[spoiler: and Slater]]
* HippieJesus - He doesn't look like a hippy per se, but the personality He uses to appear to Mary Katherine is definitely like a hippy.
* HotGod: Played with, as when Mary Katherine sees Jesus, He is a mixture of pictures she has seen of Jesus and important figures in her life, such as Skye.
* {{Jesus}}
* JesusWasWayCool
* KissingWarmUp: Mary Katherine makes out with a tree trunk.
* {{Kuudere}}: Slater
* MyBelovedSmother: Grandma Gallagher is perceived as this.
* NerdGlasses: Mary Katherine
* NunsNRosaries
* PlayingDrunk: Thomas
* PoolScene
* RaisedByGrandparents: Mary Katherine
* SchoolPlay: A talent show, but similar.
* SchoolUniformsAreTheNewBlack
* SingleGirlSeeksMostPopularGuy
* SpeechImpediment: [[spoiler: Slater]]
* SuddenlySexuality: [[spoiler: Owen]]
* SuperDrowningSkills: [[spoiler: Slater]]
* SuperOCD: Owen