The concept of house as sanctuary is one of the great clichés of shelter-magazine writing—and for good reason, as anyone who finds comfort in their home can attest. But for sisters Kourtney and Khloé Kardashian, the idea registers on a whole different level. After all, when you’re members of what is arguably America’s most famous family, with so much of your life playing out on reality TV and in the tabloids, you need someplace where the eyes of millions are not watching 24 hours a day.

The enterprising duo have found such an escape in homes around the corner from each other in a private Calabasas, California, enclave where the real-estate game is something of a celebrity swap meet. A couple of years ago Kourtney, the elder of the two, bought an 11, 500-square-foot Tuscan-style dwelling from former NFL star Keyshawn Johnson. A month or so later Khloé snapped up a nearly 10, 000-square-foot Mediterranean Revival house from Justin Bieber. Their half-sister Kylie Jenner also purchased a place here, and materfamilias Kris Jenner lives minutes away with their sister Kim (she’s crashing at Mom’s house with husband Kanye West and their children, Saint and North, while their new Axel Vervoordt–designed residence is being built).

Even in such a close-knit family, it’s surprising that Kourtney and Khloé—who have well-defined personalities and aesthetic sensibilities—would engage the same decorator, but they decided to entrust show-business favorite Martyn Lawrence Bullard with the task of tailoring the two houses to their respective tastes. “I’m amazed how many styles he can interpret, ” raves Kourtney. “Khloé’s place is glamorous, which suits her style. Mine is much more restrained and modern, which is perfect for where I am in my life.”

Bullard has known the family for years, having long or­bited in the same constellation of Hollywood glitterati. “Both of the girls were ready for something fresh, ” Bullard says. “Khloé’s house was a giant play palace built for a boisterous young man. We decided to give it some romance, bringing it back to its Mediterranean roots.” For Kourtney, on the other hand, the focus was her three children: sons Mason and Reign, ages six and one, and three-year-old daughter Penelope. “We wanted to make it sophisticated but family-friendly, ” notes the decorator. “She’s all about her kids.”

So there it is—one’s a little bit cozy, one’s a little bit rock-and-roll. Khloé, in characteristic fashion, puts a finer point on the distinction: “Our tastes are very specific and completely different, ” she says, laughing. “When we go furniture shopping, I stand there tapping my foot while Kourtney shows me modern pieces. Then we head somewhere full of exotic, beautiful things and all she can say is, ‘I like nothing here.’”

Kourtney in her home office, which is furnished with a vintage Jules Leleu desk and Pierre Jeanneret chairs; the arrangement of art includes Harry Benson's photograph of Mia Farrow and Frank Sinatra at Truman Capote’s Black and White Ball; a vibrant work on paper by Bridget Riley; and Batman, a gelatin silver print by Herb Ritts.

Bullard provided all the exotica Khloé coveted, dressing her home in a kaleidoscopic array of Moroccan, Turkish, and Middle Eastern flourishes. His coup de théâtre is the tented living room—an ethereal white fantasy presided over by a massive Levantine mirror with silent-film-era allure. That parlor opens onto a vine-covered terrace, where hanging daybeds sway gently in the Pacific breezes. As Bullard explains, “Khloé wasn’t interested in a traditional take on Moroccan style, so we cleaned up the lines and gave it a more vibrant, contemporary feel.”

Yet for all the drama of these spaces, the room that perhaps best reflects Khloé’s vivacious spirit is her gargantuan closet—a treasure chest of ensembles meticulously organized by color and style—devised from two erstwhile bedrooms. “I don’t have kids, so why not?” says Khloé, who recently debuted her talk show, Kocktails with Khloé, on the FYI channel and is working on a new makeover reality series for E!, the same network that has made Keeping Up with the Kardashians a sensation. “I was very hands-on in the design process. I’m obsessed with details, so I can be a bit controlling, but it’s only because I’m genuinely curious.”

That love of discovery is shared by Kourtney, who immersed herself in the history of 20th-century design to build the foundation of a serious collection. From the Pierre Jeanneret chairs that surround the dining table to the living room’s Oscar Niemeyer chair and ottoman to the Jules Leleu desk that anchors her art-filled office, the home brims with modernist gems.

A felicitous collision of pieces even extends into the children’s rooms. Penelope, for one, sleeps beneath a classic three-arm Serge Mouille ceiling lamp, with a neon-light artwork installed above her pink headboard. “I’m very afraid of color, ” Kourtney confesses. “But when you have kids, you can’t be so stringent. Martyn was able to introduce bright pops in a way I can handle.”

Both sisters say that taking pride in their homes was learned from their father, the lawyer and businessman Robert Kardashian, who died in 2003, as well as from their mother. “My mom has always had a vision for our houses—she taught us the joy of interior design, ” Kourtney says. “And I have vivid memories of my dad’s closet, which was always immaculate. My sisters and I are perfectionists because we were brought up that way.”

For her part, Khloé finds particular bliss in the plush neutral-hued textiles that enrich her quietly luxurious bedroom. “I don’t get a lot of alone time, so when I have a chance to relax in bed I really savor it, ” she says. “It’s like being in a Champagne heaven. Who doesn’t want that?”