Since 2007, an experimental Pentagon program has been sending teams of civilian anthropologists and other social scientists into the hardest-fought regions of Iraq and Afghanistan to pursue a mission that's both deeply controversial and increasingly important to U.S. military strategy. Social scientists work within frontline combat units to gather information and advise soldiers about the workings of the local economy, tribal structures, cultural norms and other elements of what the military calls the "human terrain." Known as the Human Terrain System, the $250 million initiative grew out of a realization within the Pentagon that soldiers didn't know enough about the cultures in which they were operating to win the hearts-and-minds battles that are crucial to a successful counterinsurgency. With General David Petraeus, the Princeton-educated architect of the military's counterinsurgency policy in charge at CentCom, the focus on non-traditional battle approaches has moved to center stage, especially in Afghanistan, where the military will deploy at least 21,000 more troops in the coming months. The Human Terrain program represents the first significant attempt to combine the strength of the military with the wisdom of the academic establishment since Vietnam. But critics say that social scientists working alongside military units violate ethical strictures and could put local civilians at risk. How the program handles these and other issues will determine its future and test the military's readiness to fight smarter wars.