Last weekend, the Italian denim brand celebrated its 30th anniversary with concerts in 17 cities worldwide, and a limited-edition pair of jeans called "Dirty Thirty." We spoke with Renzo Rosso, the company's founder (pictured), about Diesel's place in jeans history, the company's ownership of Maison Martin Margiela and Viktor & Rolf, and the brand's new home collection. (Expect to be able to buy distressed throw pillows sometime next year.)

How has Diesel helped denim become a fashion item?
I think we changed the world's attitude about how to wear it, especially here in the U.S. Denim can be everything. We have a lot of it, and a lot of treatments: They can be anything from normal pants to high fashion, even for the red carpet.

How will the global financial crisis affect you?
I can't say I'm not nervous, because the situation is so difficult for everybody. I like to see the positive. We needed a little space. There was too much inflation of everything—so many companies, so many businesspeople. This kind of crisis will clean them out and they can give space to the good companies. A professional company can cope.

What's the thinking behind your higher-end Black Gold line?
Established luxury brands are quite difficult to wear. The new consumer wants something more comfortable—high-quality, but more casual.

Do Margiela and Viktor & Rolf influence that?
No. I want to keep them totally separate. Margiela is in Paris, Viktor is in Amsterdam, Diesel is in Italy. All three must be 100-percent free to do what they like. I don't want to influence them. Otherwise they become too similar.