"Isn't this so cute?" cooed Hiba Khan, admiring a loose-knit vest glimmering with a sequined brown collar at Tysons Corner Center's LVL X clothing store. Sexy, the 21-year-old Fairfax City resident admitted, but that's easily remedied with a long-sleeve top and a properly fastened head scarf.

In the hip young Muslim crowd, modesty is always in.

"I usually try not to buy anything too flashy or too revealing, but yeah, I want to look nice," she said while at the mall one recent afternoon for a little back-to-school shopping.

With summer coming to a close and classes about to start, she and a half-dozen other college students were in search of "sister-friendly" clothes -- attire that conforms to Islamic dictates but appeals to a contemporary sense of style and beauty.

But sticking to Islamic standards of modesty isn't always easy, and it doesn't always come naturally to girls raised in the United States, where MTV and Hollywood are more likely than religious texts to set fashion standards. Choosing to follow Islam's clothing guidelines is often the result of a deep desire for cultural identity or religious soul-searching -- especially for young women such as Khan, who as a teenager decided on her own to adopt the clothing standards of her religion.

That doesn't mean she and other young Muslim women want to put aside a desire to be pretty.

"We want to look beautiful, but we don't have that pressure to be sexy," said Khan's friend Khadija Amjad, 21, of Centreville, dressed in a sleek black-and-purple ensemble that stretched to her ankles. The outfit was topped by a pink-and-purple hijab, or head scarf.

Estimates of the number of Muslims in the United States vary from 3 million to 7 million. About 150,000 live in the Baltimore-Washington area, according to the American Religion Data Archive.

Muslims, men and women, are required by their holy book, the Koran, to be modest in their attire, Islamic scholars said. How the guidelines are interpreted varies by geography and family tradition, from simply avoiding form-fitting or revealing clothes to covering oneself with a head-to-toe burqa.

"The whole thing goes back to the presence of God," said Akbar Ahmed, chair of Islamic Studies at American University. "You need to be in a state of decorum. You must ask yourself: How would God like to see me?"

Rika Prodhan, 22, a recent graduate of George Washington University, never worried too much about her form-fitting outfits and cascading hair when she was growing up in Houston. But as she matured into an observant young Muslim woman, a nagging voice in the back of her head grew louder. She recalls it telling her that the Koran was unambiguous -- the body, including the hair, should be well covered.

While in college, she gradually adjusted her wardrobe to better reflect her religious convictions, eventually purging it of clothes that revealed her ankles or wrists. Finally, after much introspection, she began wearing the hijab, a big step that she knew would forever change the way she was perceived in public.

"I tried to find every reason not to wear it," she said. "But I came to the conclusion it was like listening to your parents. We may not know the wisdom behind it now, but we'll realize it later."

Her parents, she said, actually were troubled by the decision, fearful that she was becoming "too Muslim" and isolating herself from mainstream society.

Today, though, they respect her decision and are glad she wears the hijab, which she said she sees as a sacrifice for God.

These days the hijab has become a flashpoint of controversy over women's rights, religious extremism and terrorism -- a symbol in some eyes of more radical Islam. The French government banned the hijab in schools. But for Khan, Amjad and Prodhan, it's an expression of cultural and religious identity as well as a fashion accessory to be matched with a stylish handbag or jacket.

Modest doesn't have to mean ugly, said Sarah Ansari, co-owner of Artizara.com, a San Diego-based company that sells modest clothing with a modern flare.

Her site features wide-leg pants, tops that go up to the neck and down past the buttocks, and tailored jackets that cinch in a bit -- but not too much -- at the waist. Her best-selling item, she said, is a flowing tie-dye skirt festooned with sequins, a staple offering at any youth-oriented mall clothing store.

"I don't think there's anything in Islam that precludes women from looking attractive or professional," she said. "No one says you have to look like a bag lady. Actually, the Prophet [Muhammad] was known for wearing perfume, being clean and very well dressed."

One Web site, www.thehijabshop.com, offers a line of stretchable cotton athletic hijabs that are slipped over the head or fastened with Velcro rather than wrapped. Another, www.hasema.com/shopen, sells full-body swimsuits for women.

And dozens of sites selling trendy, modest clothes have cropped up in recent years, not only for a Muslim clientele but for orthodox Jews and conservative Christians as well.

Ansari, who is Muslim, said her customers range in age from 13 to 65 and come from a variety of backgrounds.

For Amjad, Khan, Prodhan and their friends, mainstream stores such Banana Republic and H&M offer enough choices. The latter, a Swedish retailer, is especially popular because its up-to-the-minute European styles tend to cover more of the body than standard American offerings, they said.

During their shopping trip, the young women pointed out their favorite styles of the day: peasant skirts, billowy gaucho pants that fall to the ankles and tunic-style tops that end far below the waist. They tend to buy jeans a size bigger than their actual size, fix ankle-baring skirts with a chic pair of boots and pair sleeveless tops with concealing blazers.

They will, however, occasionally buy an outfit that doesn't follow the rules, saving it for "sisters-only" -- or women-only -- events such as like sleepovers or bridal parties.

The hijab adds another accessory to the mix, they said, and has the bonus of covering up a bad hair day, Khan joked.

In all seriousness, she said, the hijab is a garment for the body and the soul.

"It lifts you up as a person," she said. "You're seen more as a person than that girl with her hair flowing around."

From left, Khadija Amjad, 21, of Centreville, Nida Khan, 18, of Fairfax City and Hiba Khan, 21, of Fairfax City shop for clothes at LVL X at Tysons Corner Center. Rika Prodhan of Houston and Nida Khan at Tysons Corner Center. Honoring Islam's tenets on modesty, the two wear "hijabs," or head scarves.Khan, left, a George Mason University student, and Khadija Amjad, a George Washington University student, check out the clothing selection at LVL X at Tysons Corner Center.