From The Movie Snob:

Mean Girls (B). A friend of mine warned me against this movie, but her taste is suspect so I saw it anyway. I thought it was funny and entertaining. Lindsay Lohan (Freaky Friday) plays Cady, a 16-year-old girl who has lived in Africa and been homeschooled by her scientist parents her whole life. They move to Chicago, and Cady goes to school for the first time. There she befriends a couple of outsiders (goth chick, homosexual guy) but also finds herself adopted by "the Plastics," a clique of cool, popular, and yes, mean girls. I can't say that the movie really broke any new ground, but it was a fun diversion. If you saw Freaky Friday, you may get deja vu throughout this movie because the shtick is pretty much the same--unusually mature girl finds herself thrown into modern American high-school life and finds that maturity is no defense to the grim realities of that harsh social order. Enjoy!