Even more fulsome is Robert Thorne, the girls' longtime agent, business manager, and president of Dualstar Entertainment, the umbrella organization for their multitudinous business activities. On June 13, shortly after their high school graduation, the girls will turn 18, legally able to serve as officers in their own company. And, says Thorne, "June 13 is going to be the biggest media birthday in global experience."

That's a long way from the audition in 1987 when the 4-month-old daughters of David and Janette Olsen were picked out of a lineup to share the role of Michelle Tanner on Full House. The sitcom would run for eight years and make the two child stars genuine celebrities. But a lot of kid actors become popular before pulling a Danny Bonaduce, destined to wind up as a guest on some reality television series.

What made the difference for Mary-Kate and Ashley was a combination of iron-fisted control of their careers by themselves and Thorne; their still squeaky-clean, girls-next-door image, also jealously guarded; and the inherent appeal of twins. And then there's luck. A chance happening in 1991 may have influenced their success even more than the rest, and it certainly built the foundation for their future.

That year the girls recorded a disk of songs distributed by BMG Kids, the children's label of German music and publishing conglomerate BMG. The CD sold half a million units, a solid showing. But what made the deal special was that Thorne, who had just joined up with the two, granted BMG the right to make one music video.