Sports Illustrated magazine, already in a league by itself among sports publications, is expanding its franchise.

Time Inc., SI's parent, this week rolled out the first issue of Sports Illustrated for Kids, a new monthly magazine aimed at youngsters between 8 and 13 years old. The new SI won't have an annual swimsuit issue, like the one for big kids, but it will have feature articles, games, posters and trading cards.In addition to being a potential moneymaker for its parent, the magazine hopes to accomplish an important social function: helping children to read.

Half of SI for Kid's 500,000 monthly copies will be donated to 1,200 schools nationwide, along with teachers' guides. The other half will be sold to subscribers for $15.95 a year or will be available at newsstands for $1.75 a copy.

Time Inc.'s strategy for selling advertising in SI for Kids also is different. Instead of selling pages piecemeal like most publishers, the company has sold packages that entitle an advertiser to 10 ads a year for a minimum payment of $250,000. Thus far, 29 of the 33 available sponsorships have been sold to such companies as American Airlines, AT&T, RJR Nabisco, Procter & Gamble and sneaker makers Converse, Nike and Reebok.

Advertisers "like the educational aspect, but they also realize they'll be reaching America's future consumers," said Ann Moore, publisher of SI for Kids. "Brand identity starts at an early age." She said the same concept applies to Time Inc., which hopes the young readers will become Sports Illustrated subscribers.

Moore wouldn't disclose Time's investment in Sports Illustrated for Kids or the magazine's break-even point. Sports Illustrated, founded in 1954, took more than 10 years to turn a profit.

SI for Kids is stepping into a relatively competitive arena. According to Standard Rate and Data Service, a magazine-trade publication, 47 magazines compete for the attention of young readers, from comic books and Tiger Beat to The Muppets magazine and Boy's Life.

But SI for Kids has strong family connections. Its older sibling, Sports Illustrated, is the third highest-grossing magazine in the nation, with $295.1 million in advertising revenue through November, placing it behind Time and TV Guide, according to the Publishers Information Bureau. SI, which turns 35 next year, has a circulation of 3.4 million.

Originally titled Sports Illustrated Jr. - the name was scrapped after research indicated children found it too male-oriented, said managing editor John Papanek - the younger SI is written for children on a fifth-grade reading level and has slightly larger type than the grown-up version.

The 92-page premiere issue has Chicago Bulls basketball star Michael Jordan on the cover and contains a how-to article featuring Mary Lou Retton and stories about Redskins quarterback Doug Williams and Olympic star Jackie Joyner-Kersee.