Bart is shipped off to military school after a particularly destructive prank (lining up 15 police bullhorns and unleashing a soundwave that shatters all the glass in town) -- and Lisa tags along (despite that the military school is boys-only and the other cadets don't take kindly to change) after finding public school education has become a grind.
!!Tropes of this episode: [[YMMV/TheSimpsonsS8E25TheSecretWarOfLisaSimpson YMMV Here]]
* AmbiguouslyGay: Franklyn, the "girliest cadet" before Lisa joins.
* BaitAndSwitch: Homer and Marge at the end.
* BadassBookworm: Despite the other cadets hating her because she's not a boy, Lisa loves the military school because it has rigid structure and teachings.
* BeCarefulWhatYouWishFor: Lisa comes to the school looking for a challenge but nearly gives up when confronted with The Eliminator. Bart lampshades this "I thought you wanted a challenge".
* {{Determinator}}: Lisa didnít let the other students, all male, get the best of her. They tried to get rid of Lisa on [[NoWomansLand grounds of her sex]] and proved that she can be just as tough as they are.
* GoneHorriblyRight: Homer and Marge wonder at the end whether or not it's a good thing that Bart now has much more confidence and is trained in several forms of unarmed combat.
* HypocriticalHumour: Following BeCarefulWhatYouWishFor above.
-->'''Bart:''' I thought you wanted a challenge?
-->'''Lisa:''' Yeah, a challenge I could ''do''.
* JackieRobinsonStory/ YouGoGirl: Possibly attempted by Lisa but ultimately subverted. She gets through the semester but the cadets don't change their opinion of her and she doesn't prove better than them at any of the subjects.
* MortonsFork: As Bart and Lisa are forced to do pushups, Lisa is asked "Don't girls like doing pushups in the mud?". Lisa, in turn, asks [[GenreSavvy "Is there any answer I can give that won't result in you making me do more push-ups?"]], to which, after much deliberation by the other cadets, is "No."
* NoodleIncident: Who had the idea of setting up a field trip to the police station?
** Probably Principal Skinner, since Springfield Elementary is so low-rent that a field trip to the police station is all they could afford.
* ParentalFavouritism: Marge and Homer send ''Lisa'' a cassette intended to comfort her yet they don't send Bart anything, not even considering his feelings about how he is at the school.
* SmarterThanYouLook: Thanks to his years with a slingshot (and the assumption that because he's a public school student, he knows how to handle guns and other weapons), Bart knows how to use a rocket-launcher. In fact, Bart is such a master, he gets Skinner's car from a far distance away.