On her sixteenth birthday, Sabrina Spellman finds out that she is a witch. However, instead of helping her, it actually makes life more difficult, especially after she gets on the wrong side of head cheerleader, Libby.
In order to find out what Libby has been saying about her and Jenny, Sabrina gives her a piece of cake covered with truth sprinkles. However, when her teacher shares the cake with students and teachers, Sabrina finds that the truth hurts.
In an attempt at earning some money to buy roller blades, Sabrina takes a job babysitting a little boy. However, when she is trying to calm him down, she inadvertently casts a spell which turns him into a man.
Sabrina makes three wishes come true for her unsuspecting friends: Jenny gets elected student president, Harvey becomes a football star, and Mr. Pool becomes rich. Soon she learns the truth of her aunts' warnings that one shouldn't meddle with the fate of others: Jenny is crushed when she learns the student president is merely a rubber stamp assistant to the principal, and resigns in favor of Libby, Harvey really can't play football and is injured on the field, and Mr. Pool's success at alchemy turns him into an obnoxious blow hard.
When she's forced to attend a family affair, Sabrina sends a clone to Harvey's party, where the simple-minded stand-in (who can only speak three sentences) agrees to streak naked in order to liven up the festivities. Meanwhile, the real Sabrina desperately tries to ditch her relatives: an obnoxious socialite and her brat of a daughter, whose hobby is putting people she dislikes into jars. Knowing Harvey plans to dress as James Dean, Sabrina muses about the real star, but when her aunts give her a special Halloween present of a half hour with the dead person of her ...
Sabrina tires of Libby's constant teasing-- which worsens when Sabrina joins a science club-- so she gives the tormentor a taste of the taunting by turning her into a nerd. Meanwhile, Zelda wants Hilda to throw out some very old items. Tired of watching Libby treat people badly, Sabrina decides to give Libby a taste of her own medicine by transforming her into a geek. However, when Libby succeeds in turning her fellow geeks against the entire school, Sabrina must find a way to unite her classmates before the plan backfires.
After Salem stows away in her backpack and gets her thrown out of the local pizzeria, Sabrina washes her hands of the cat, feigning unconcern when the feline fails to return for Christmas dinner with visiting cousin Monty. When she discovers that Salem has in fact been catnapped by a stubborn little boy named Rex, Sabrina launches a desperate plan to rescue him by impersonating Santa Claus.