In 1989, Hallam Hurt, a neonatologist in Philadelphia, started recruiting poor inner-city women for a study of how cocaine use during pregnancy affects the developing fetus. Dr. Hurt enrolled women who had used cocaine while pregnant and balanced them against a control group of equally poor women who had not taken any drugs. Years later, when the physician conducted follow-up intelligence tests, the results provided a shocking indictment of American society. The tests showed that children exposed to cocaine in the womb had a mean IQ of 79 at age 6, a full standard deviation below the average. Even more disturbing, though, were the results from the control group. The 6-year-olds who had never been exposed to drugs had virtually the same IQ as the children who had endured cocaine running through their veins while inside the womb. Dr. Hurt's data suggests that while cocaine no doubt does cause harm in utero, poverty itself presents an even graver threat to a child's intellectual development. "Growing up poor is bad for your brain" says Martha J. Farah, director of the Center for Cognitive Neuroscience at the University of Pennsylvania, who has collaborated with Dr. Hurt in recent years. What Ms. Farah and other researchers are now trying to tease apart is exactly how poverty--which affects 12.8 million people under age 18--takes its toll on the brain. The preliminary results from her studies and others are pointing the way toward methods that might ameliorate some of the effects of poverty.