Look at the windows of your favorite clothing stores. Everywhere from Anthropologie to Marshalls, retailers are selling a mash-up of looks from decades past, including cap-sleeved blouses (1950s), skimming shifts (1960s), and preppy tennis dresses (1980s).

Which means the time is right for Center City designer Sarah Van Aken.

Following in the footsteps of Marc Jacobs and Catherine Malandrino, Van Aken specializes in mixing elements from previous decades to create a modern signature style.

"I definitely have a 1940s sensibility," said the designer, 31. "But I'm influenced by the round necklines of the 1920s and the jersey fabrics of the 1970s as well."

Van Aken is already well known throughout Philadelphia's fashion community for her Van Aken men's and women's custom-tailored shirts. A former executive manager at the Marathon Grill, she launched a line of restaurant uniforms in October called Van Aken Signature; waiters and waitresses at New York's Gotham Bar & Grill wear her purple- and white-striped preppy designs.

But I think she'll be best known for her ready-to-wear line, SAVA, which has grown from six silky camisoles to a 30-piece fall grouping. The collection will debut in boutiques in Washington, Los Angeles and Dallas this year. Molletta, in Old City, and the Bryn Mawr boutique Skirt will also carry the line, starting in midsummer.

For a first collection, SAVA is impressive, as Van Aken has a definite point of view. Some pieces are simple: A wrap dress that comes in burgundy and black is an easy sell. A deep V-neck brocade shift with metallic strands is dressy and decorative.

Many of her camisoles - my favorite is a wide-strapped empire-waist dress with expertly placed tucks - have been elongated into shiny maroon and cobalt-blue dresses. The high-waisted pencil skirts and camel-hair cropped jackets that Van Aken is often seen out on the town wearing can be mixed into any working girl's wardrobe.

"All of her stuff has hints of the early 1950s and 1970s; it's like a modern version of a classic," said Christa Bevilacqua, a co-owner of Molletta. "She hits each timetable with a sophistication across the board."

The blend trend is a strong one this summer, thanks in part to our continuing fascination with the dress.

Coatdresses are fashionable, as are empire-waist dresses, as is my latest addiction, the trapeze dress. This summer, expect to see women move through decades with each change of clothes. In other words, it isn't Katharine or Jackie, it's both.

"The future may be far ahead of us, but the creative minds of the day's fashion designers are all about taking the prior influences and reinterpreting them," said Tom Julian, director of trends for McCann Erickson, a New York-based advertising agency.

"There are the sculpted and structured 1940s and 1950s looks and the resort-wear 1950s, which also reminds us of the 1980s," he said.

What these fashions have in common is that they lean more toward classic than casual. And that's part of the reason Van Aken set out to be a fashion designer.

"I just got tired of not dressing up anymore," said Van Aken, wearing a pencil skirt and cinched jacket from her line. "There is definitely a void in the market for sophisticated clothing that fits everyday women."

Van Aken graduated from the University of Delaware in 1998 with a degree in fine arts. That year she moved to New York, where she worked in the garment district for two years. In 2000, she moved back to Philadelphia to work at the Marathon Grill, where she rose to executive manager.

She left Marathon Grill at the end of 2004 to write a detailed business plan. She wanted to finance her company without the help of a backer so that her vision - designing wearable clothes for ordinary women - would not be muddied.

"Who in their right mind would want to give me a half million dollars to start a fashion company?" she asks, rhetorically.

So far, Van Aken has invested more than $100,000 in her businesses, all of which were launched early last year. The profits from her custom shirt and uniform ventures provided the money for the Italian and French fabrics used in the SAVA line.

One thing that has helped her remain independent is that she has some control over the manufacturing. While working at Marathon, she met Imitiaz Karim, from Bangladesh. Through his connections, she opened a manufacturing plant there, where the majority of her ready-to-wear line is made (her custom shirts and uniforms are made in the United States).

Van Aken also finances her company through selling real estate with Philadelphia-based developer Wayne Zukin, who owns the building at 1700 Sansom St. where she houses her operation.

There, she is currently working on her spring 2008 collection, a series of dotted and printed fabrics tacked to the wall. That series will still include her camisole dresses, with their 1920s feel. The rest, she's still trying to figure out.

"I really want to be among the biggest apparel companies in the country," Van Aken said. "Who knows, maybe I can be the next Banana Republic."

Sarah Van Aken can be reached at 215-496-0408. Her studio is at 1700 Sansom St., 7th Floor, 19103.

Contact fashion writer Elizabeth Wellington at 215-854-2704. Read her recent work at http://go.philly.com/elizabethwellington.