We've been hearing for years now about racial and ethnic disparities in health care; both The New York Times and the AP reported this week that black diabetics, for instance, are far more likely to have a leg amputated than a white with the same disease, or that a black woman is less likely to get a mammogram than her white counterpart.

But evidence has mounted that disparities are not just racial, cultural, or even socioeconomic. They are also regional, or geographic. Some parts of the country practice a far more intensive form of medicine than others—sometimes doing too much more, running up procedures and costs and inpatient bills and specialty consults without any true health benefits. And sometimes they do too little; millions of people do not get the proven benefits of primary and preventive care and screening.

"In my book, health care is local, just like politics, so you're going to see a lot of differences in what communities do," said Dr. Bruce Siegel, the George Washington University professor who will direct an ambitious new health quality program for the Robert Wood Johnson Foundation.

RWJF has just announced a $300 million initiative to improve the quality of health care, working with a range of doctors—and nurses—as well as hospitals, health plans, community groups. The project will unfold in 14 communities—together covering more than one-in-10 Americans. RWJF calls "Aligning Forces for Quality" the largest effort of its kind ever undertaken by a U.S. philanthropy. The foundation says the goal is to "lift the overall quality of health care, reduce racial and ethnic disparities and provide models for national reform."