Dresses remain a key to retail success — and there's no sign of a slowdown.

Whether shoppers' ongoing interest in dresses is being spurred by simplicity or post-feminism values is open to debate among retailers, but they agree the category will remain robust through fall and even into next spring. And as dress sales boom, they are boosting growth in other categories, from leggings for fall to key accessories such as shoes and belts.

Dress sales generated $5.06 billion at retail for the 12-month period ended April 30, up 30 percent from the $3.88 billion the prior year, according to The NPD Group Inc., the Port Washington, N.Y.-based market research firm.

"Dresses are on fire right now," said Ken Downing, senior vice president and fashion director at Neiman Marcus. "The fall runways had one great dress after the other. Even in the resort collections we are seeing now, the dress is still of-the-moment. There are numerous types of silhouettes and they look equally terrific."

With dresses selling across the board, Downing was hesitant to single out any particular label, but allowed: "The Neiman Marcus customer always loves something a little more feminine, detailed and [colorful], of course. There's interest in embellishment and embroidery, and we're seeing that as we move into resort."

The fact that designers continue to play with different shapes and silhouettes only helps the cause, Downing said. Heading into fall, he expects the sheath and chemise to catch on, especially when paired with "a great little jacket" or lightweight coat. "Depending on a person's body type and personal taste, there is a dress for everyone," he said.

For the past five seasons, Louis Boston has been building on its dress sales and "that's what is selling," said owner Debi Greenberg.

She offered a more introspective view of the trend. "The dress was everything for my mother's generation in the Fifties — from the housedress to the cocktail dress. In the Sixties, it was the mini, and in the Seventies, separates took over. Separates were comfortable, and in the Eighties, the power suit entered the workplace as a way to look professional. Then there was the casual and dot-com trend and everyone was wearing jeans with nice tops. It was comfortable, casual and a little sexy and flippant. The way times are now, the U.S. is not as rich and domineering. In a global society, Americans aren't top dogs anymore and that flippancy is not as appealing."