"You've got to keep moving forward," the mother of three tells Vogue's Age Issue of her decision to embrace her silvery side six years ago.
Inside the magazine, McMenamy, photographed by David Sims, looks '70s chic in a floppy black hat, crisp white shirt, charcoal gray skirt, camel-colored trench, and waist-length gray tresses.
"I thought all that gray hair would make a beautiful picture," says McMenany, who has Josh Wood at Real Hair in London lighten the black streak at the center of her head to match the rest. "You can get older and still be rock 'n' roll."
McMenamy's not the only one who considers gray to be cool. Granny strands ruled Gareth Pugh's and Proenza Schouler's Spring 2010 runways, and celebrities including Lady Gaga, Kate Moss, and Pink have all added in streaks of silver.
"I think there's beginning to be a backlash to this eternal quest for anti-aging that has led to so many celebrities looking falsely nipped, tucked, and squeezed," said UK Vogue beauty and health director Nicola Moulton, according to the London Telegraph.
"Stopping at nothing to look just a few years younger is starting to look dated itself... which is why I think we're seeing models and younger celebrities embracing things like wrinkles and a smattering of gray. The bottom line is, it doesn't stop a woman looking beautiful -- on the contrary, it just makes her look more attractive by speaking volumes for her confidence."
Rod Stanley, editor of Dazed and Confused, agrees. "Kristen looks amazing and the fact she has gray hair is just part of who she is," he says of McMenamy, who posed for the issue in a furry jacket and pants and other earthy ensembles.
"She's happy with her gray hair and so were we, and that's how we photographed her. I think it goes to show that it's all about individuality and originality."
Plus, read the debate about whether it's OK to go gray.