Under heavy pressure from government regulators and insurance companies, more and more physicians across the country are learning to think like entrepreneurs. As recently as the late 1990s, there were only five or six joint M.D./M.B.A degree programs at the nation's universities, said Maria Y. Chandler, MD, a pediatrician with an M.B.A. who is an associate clinical professor in the medical and business schools at the University of California, Irvine. "Now there are 65," she said. Mark V. Pauly, a longtime leader of the healthcare management program at the Wharton School at the University of Pennsylvania, said, "A light bulb went off and they realize that healthcare is a business." James S. Kuo, MD, said he was a third-year medical student at Penn when he decided to go to business school, too. After receiving his M.D. and master of business administration degrees, he jumped to a Wall Street job with a large health care venture capital firm. Kuo went on to manage several heathcare funds and later led several small healthcare companies.