(Business 2.0) – At a time when most banks are cutting back on brick and mortar, Washington Mutual has been on a building binge. The nation's seventh-largest bank plans to open 250 branches this year. It's the latest twist in a relentless growth imperative that saw Seattle-based Washington Mutual increase its assets 180-fold since 1990. CEO Kerry Killinger explains how it all works.

We're going after the broad middle market. That contrasts with competitors, who focus on the high end and make others feel unwanted.

To get our customers in the door, we've redesigned our banks to be like a store. Customers told us that they're usually confused about where to go in a traditional bank. So we put a concierge at the entry. Customers said they dislike standing in line. So we have employees roaming around to help people. Then they told us bank branches are boring, so we made the interior decor closer to what you'd see in a Gap or Starbucks.

When we move into a market, it's a community experience. We open 30, 40, 50 stores in short order. In our case, there's also a big advertising umbrella. We try to get that critical mass of name and customer recognition fairly quickly. No one in banking had figured out how to profitably expand without acquisitions. We have. --INTERVIEW BY THOMAS MUCHA