Growing up in poor urban neighborhood, Carl Hart watched crack cocaine ravage the lives of his relatives. Early in his research career, Hart set out to find a neurological cure for chemical addiction. But as he began studying addicts, he found that there was more at issue than the neurochemical properties of the illicit drugs. In groundbreaking experiments, he offered crack addicts a choice between a dose of the drug or a monetary reward. When the dose was smaller, addicts often chose the money. When the monetary reward increased, all the participants opted for financial gain over getting high. A tenured science professor at Columbia University — and the first African-American to hold that distinction — Hart has leveraged his research to advocate for policy reforms. He argues that law enforcers focus too heavily on prosecuting drug users while ignoring poverty, racism, and other socioeconomic conditions that spur substance abuse and crime.