Sunday's life as a child model begins when her braces come off and her mother, declaring her adorable, has pictures taken and sent round to agencies. (Mom's own figure-skating career was cut short by Sunday's birth, a fact the daughter does not forget.) At first Sunday is attracted by Mom's vision of TV-commercial stardom, even though she waits a long rime for her first audition and even longer for her first callback. Her luck changes when, at the suggestion of fellow-model Heather's professional mother, she does her hair into one big braid--and gets a dog food spot she's trying for. Then comes a central role in a toothpaste ad, and finally a part with Heather in a suntan lotion commercial to be filmed on location in Florida. But the career is hard on her school work--soon she's flunking science--and she feels left out by the other kids whose extra-curricular life she no longer shares. She's hurt when classmates put dog food in her lunch bag and toothpaste in her sneakers--though, remembering the studio direction, ""Smile if it kills you,"" she comes back like a trouper: ""At least I won't be getting any cavities in my toes!"" Worse, formerly successful Heather is headed for Transition, that child model's doom: in Florida, an eruption of zits has her scratched from the suntan film, and Sunday must save her from suicide on the jetty. More affecting, overweight little brother Edward feels left out, and their father, distressed by his long hours and the family's distorted priorities, wants to move to Arizona. Sunday's decision, then, is inevitable, and neatly executed. . . with a snip of the scissors and a toss of the braid into the wastebasket. Shyer doesn't take this beyond the predictable problems of the professional child, but that theme has the predictable dual appeal of the deglamorizing peek at backstage glamor, and Shyer handles it with more style, less soap, than many.