For an apparel retailer that faces the daunting challenge of selling to fickle teens, Aéropostale is nothing but consistent. How else do you explain its Hot Growth ranking -- No. 5 for the second year in a row? The New York-based mall retailer, with 601 stores, has achieved this by following a careful formula: Let rivals like Abercrombie & Fitch (ANF) and American Eagle Outfitters (AEOS) set major apparel trends, but follow them quickly. And at much lower prices. Aéropostale backs this up with sophisticated consumer research to pinpoint trends that will sell well.

Over the last three years, its annual sales have climbed an average of 45.4%, driven by rapid store expansion and strong sales at stores open at least a year. Average annual profits jumped 95%. In a bid to stave off the inevitable saturation of its stores, the company this summer will launch a second chain called Jimmy'Z, which will target a slightly older shopper with California- inspired casual clothing. But being as consistent will be harder with two chains to manage.

Julian R. Geiger, 59