Every year since 2003, Fortune has dubbed Linda Dillman one of the 50 most powerful women in business. And why not? In 2003, while serving as chief information officer for retail giant Wal-Mart, she launched perhaps the world’s most envied RFID supply tracking system. As is Wal-Mart’s practice, in 2006 Dillman switched career paths and became executive vice president of risk management and benefits administration, making her responsible for health coverage for the nation’s largest private-sector employer. She sets benefits policies for more than 1 million workers—or “associates,” in Wal-Mart speak. She’s in the forefront of some of health care’s most pressing issues: Wal-Mart, along with other big businesses and labor unions formed Better Health Care Together to advocate reform; the retailer joined five other large companies to build a personal health record system called Dossia; and the company must stave off union-backed legislation to enhance its benefits package. Dillman recently spoke with H&HN Senior Editor Matthew Weinstock.