As is the case at just about any high school, the students at Mica Area High School know that the key to not being picked on is to fly under the radar, and make yourself as invisible as possible. Nobody, however, has ever told our main character, Stargirl Caraway, this. Having been home schooled for fifteen years, she arrives at Mica in the tenth grade, and there's nothing conventional about her.
The story is told from the perspective of Leo Borlock, an eleventh-grader who falls head over heels in love with Stargirl.
Stargirl is undeniably eccentric, and her classmates initially react to her odd behavior with suspicion and seem to be afraid of socializing with her. As time goes by, however, Stargirl's individualism and unique character inspires some of her classmates to think outside the box and become more open-minded. Later in the year, however, the tide turns against Stargirl, and her peers unite in rejecting her.
It is in the second half of the novel that Stargirl and Leo start dating, but Leo makes the mistake of trying to change Stargirl and make her more conventional—which she firmly is not. Leo eventually breaks up with Stargirl and ends up regretting it later in life.
This coming-of-age story, or bildungsroman, forces young readers to think about what it means to stand out and what the consequences of ostracizing someone are.