Must've Been a Beautiful Babe

It's hard to picture celebs like Leo, Sarah Jessica and Nicole as diaper-clad tots, but even those famous folks were once mere munchkins. Stroll down memory lane as we peek at big stars back when they were little tykes.

DIVA-IN-TRAINING

Before she got "Dirrty," pigtailed cutie Christina Aguilera (pictured in 1985 at age 4) was all wide-eyed innocence. Yet even as a little girl, Aguilera had a big voice; she sang the national anthem at hometown Pittsburgh Steelers games by age 10, PEOPLE noted in 1999. In January, the dyed and pierced diva wowed the crowd at the American Music Awards.