Christie Brinkley (search) was a supermodel before there was such a word, and a large part of her popularity came through 20 years of CoverGirl (search) ads.

With her blond hair, blue eyes and curvy-yet-athletic figure, Brinkley's all-American looks made her the perfect match for the all-American cosmetics company. The association began in 1976.

Brinkley and CoverGirl parted ways in the mid-1990s, but it was an "amiable separation." Put it this way, she continued to use CoverGirl makeup, she said with a laugh in a recent phone interview.

When the company approached her earlier this year to rekindle their relationship, Brinkley didn't blink.

After all, it's fun work if you can get it, says Brinkley, who spent this day romping on the beach with her horse, dog and her two younger children, daughter Sailor, 7, and son Jack, 10, with the cameras rolling for the TV and print ads that break this week.

"We've been having a ball today. It's like a time warp. It's as if those 10 years between never happened," she says by cell phone from the shoot in the Hamptons on New York's Long Island.

Of course, what is different is that Brinkley is now 51 and she's pitching a line called Advanced Radiance, makeup intended for women 30 and older.

"There is such an age phobia in this country and this ad is showing me being comfortable with the age I am. I think it's a good positive image, something you don't see enough of. ... CoverGirl is making an effort to show a wide range of beauty -- different ethnicities and age groups," she says.

Indeed -- Brinkley joins a company stable of models that includes Queen Latifah (search),Elsa Benitez (search), former Miss Universe Amelia Vega (search) and Molly Sims, who picked up where Brinkley left off as the healthy, fun-loving beach type.

"Her public perception as a mother is very strong," says Andrew Sacks, president of AgencySacks, a Manhattan-based advertising agency that concentrates on the upscale market.

"People like her. There's not a diva association. For a very wholesome American brand, it's a perfect match," he adds.