they may be growing up, but muniz, sullivan and berfield will still be boys!

"i really like gross things"
the brain sits on the desk next to a package of cookies. suspended in liquid and sealed in a plastic jar with a pink lid, the organ is whitish and dissected. it once belonged to a sheep. now it's the property of frankie muniz, the star of fox's malcolm in the middle, who's been studying the brain for school in his on-set tutoring sessions. well, what's homework for a teenager is an object of pure fascination for a 10-year-old boy. "i really like gross things," says erik per sullivan, who plays malcolm's younger brother, dewey, during a break in his own on-set tutoring. "i'm dying to get my hands on it." what if the brain is slimy and squishy? "probably is."

muniz will likely one day give sullivan his brain. he's growing too old for such things, a fact that has eluded neither the show's producers nor its loyal fans. the triumphant, award-winning malcolm in the middle has arrived rather early in its third season at a crossroads. the show about the painful hilarity of childhood and adolescence is having a growth spurt of its own. muniz and justin berfield who plays malcolm's bullying older brother, reese are both 16. a peek at the pamela anderson and carmen electra posters in berfield's dressing room tells you what's on his mind these days. as for christopher kennedy masterson, who plays alaskan exile francis, he's a 22-year-old acting "veteran" (he's been appearing in front of the camera since age three) who considers himself the elder statesman of the group.

"that was the biggest change for the year the kids have grown so much that we couldn't keep them in overalls. it would be ridiculous," says malcolm creator and executive producer linwood boomer, while observing muniz, sullivan and berfield film a scene in which the older boys discuss seeing a naked woman, leaving poor dewey baffled. ("big deal! mom walks around here naked all the time!") "the show is sort of becoming more about girls and friends."

unlike other family comedies that have simply added young characters along the way to compensate for aging cast members (remember the brady bunch's cousin oliver?), malcolm has instead embraced the boys' growing up as a way to tell new stories. "when we started, frankie was still a little boy, not only in look but in manner," says bryan cranston, 46, who plays affable hal, the boys' father. "now he's very much a teenager. so as the boys get older, i think you're going to find more story lines about their maturation." this season, reese got his driving learner's permit and francis got married.

the boys are moving on in real life, too. muniz is now a movie actor (big fat liar), ruffles 3d's pitchman and car owner (he paid about $100,000 for the volkswagen jetta featured in the film the fast and the furious).

masterson shares a house in the los angeles suburbs with laura prepon of that '70s show. he thinks of himself as more of a mentor than an older brother to his cast mates.

"i always make it very clear to them that i'm around and that they can come to me," masterson says. he has a collection of those "when i was a kid..." stories handy. for example, when muniz consulted with him about buying a car, masterson told him that when he was modeling as a child, his parents let him spend just two dollars per job of his earnings. "when i was five years old, that meant i could buy a matchbox car," he says.

frankie finds romance
malcolm, whose biggest problem used to be dealing with his parents' decision to put him in a class for the gifted, instead now flails his way through the tricky territory of teen courtship. "i'm getting so much older, and malcolm's getting so much older, too," says muniz. (malcolm's actual age is never specified.) "so i'm getting to do some cool things." like kissing scenes? "not as much as i thought there was going to be," he says, sounding disappointed. "there was the 'malcolm's girlfriend' episode and then one scene last year. so only twice so far!"

but being famous doesn't make the boy-girl thing any easier for the actor. fox.com message boards buzz with rumors that muniz is the boyfriend of hilary duff, 14, star of the disney channel's lizzie mcguire. "i wish," muniz says with a sigh. then he switches gears, using the rapid-fire speech (with arched eyebrows) that makes him perfect for the loquacious malcolm. "we are very, very close. i mean, we're like a couple. we really, really like each other like that. but we don't say we are. so, like, it will change soon. i think."

behind the wheel
muniz has other loves in his life besides girls. specifically he has three: the los angeles clippers basketball team. cars. and his career. his dressing room is decorated almost entirely in clippers paraphernalia. "ive just always liked them" he says with a shrug. " i want to own them i mean i dont think i ever will they cost a fortune." as for cars he already owns two. a pickup truck and the souped up jetta. muniz boasts that the jettss sounds system is so powerful that he can "turn on peoples car alarms when i drive by." "and thats not even when its loud." he also claims he once raced along a freeway at 150 miles pe hour. "i want to be a stunt driver." he says "i mean i seriously loive driving." i want a lot of cars i love cars. the internal combustion engine has also captured the fancy of berfield who bought himself a new silver mercedes. c320 for his most recent birthday. quieter then muniz and sweeter than his tv alter ego berfield chose the car for its saftey record. "im afraid to go fast" he says. "i dont want to wreck my car" its dangerous. speed is nothing to joke around with.

but being famous doesn't make the boy-girl thing any easier for the actor. fox.com message boards buzz with rumors that muniz is the boyfriend of hilary duff, 14, star of the disney channel's lizzie mcguire. "i wish," muniz says with a sigh. then he switches gears, using the rapid-fire speech (with arched eyebrows) that makes him perfect for the loquacious malcolm. "we are very, very close. i mean, we're like a couple. we really, really like each other like that. but we don't say we are. so, like, it will change soon. i think."

behind the wheel
muniz has other loves in his life besides girls. specifically he has three: the los angeles clippers basketball team. cars. and his career. his dressing room is decorated almost entirely in clippers paraphernalia. "ive just always liked them" he says with a shrug. " i want to own them i mean i dont think i ever will they cost a fortune." as for cars he already owns two. a pickup truck and the souped up jetta. muniz boasts that the jettss sounds system is so powerful that he can "turn on peoples car alarms when i drive by." "and thats not even when its loud." he also claims he once raced along a freeway at 150 miles per hour. "i want to be a stunt driver." he says "i mean i seriously love driving." i want a lot of cars i love cars. the internal combustion engine has also captured the fancy of berfield who bought himself a new silver mercedes. c320 for his most recent birthday. quieter then muniz and sweeter than his tv alter ego berfield chose the car for its safety record. "im afraid to go fast" he says. "i dont want to wreck my car" its dangerous. speed is nothing to joke around with.

cautious words from malcoms reckelss reese, but berfield is nothing like his character. during the interview he proudly mentions his volunteer work on behalf of ronald mcdonald house charities, the nonprofit organization for which he serves as youth ambassador. " justin looks like a punk," says masterson. "but hes the nicest kid ive ever met." and dirt free adds cranston. "he learned early on how to keep clean i mean hes a teenager right? but he washes his face and makes sure he puts on sunscreen.

summer break

now that theyre almost finished filming the guys are considering which movies to make over the summer. "i dont want to take a break" says muniz. "im going to be an adult soon, and i wont be able to play certain characters. so i need to do everything while i can now. if i keep going when im 30 ill retire. sulivan was balking at a script that would require him to gaspkiss a girl. he asked cranston for advice. erik said "say your me and someone asks you to be in a movie but you have to kiss a girl, now i dont want to kiss a girl. recalls cranston. his advice, "believe it or not when you get to be frankies age youre going to go "oh" i get to kiss a girl."

in the meantime sullivan continues to pursue the gross rather then the soft and curvy as boys his age should. on one of the last days of shooting he, muniz and berfield travel to a seedy area alongside a graffiti covered cement storm drain for an episode in which they explore the sewers. while muniz and berfield are blasé about the adventure, sullivan is positively jazzed. and when a scene ends with him skipping into a large pipe he doesnt return after the director yells cut. finally boomer shouts for him "erik come out of the sewer!" sulivan emerges all smiles. this is cool!" a better statement of quickly fading boyhood there may never be.