The “war on drugs,” beginning in the 1980s, represented a profound shift in the way in which the United States practiced law enforcement, and ushered in a new era in American policing. Overall, between 1980 and 2003, the number of drug offenders in prison or jail increased by 1100% from 41,100 in 1980 to 493,800 in 2003,2 with a remarkable rise in arrests concentrated in African American communities. This precipitous escalation began as the result of a tangible shift in law enforcement practices toward aggressively pursuing drug offenses. This report analyzes the implementation of the drug war on the “ground level,” and how it has played out in arrest patterns in the nation’s largest cities. Our examination reveals broad disparity in the use of discretion regarding the scope of drug arrests, and consequently its effect on the communities most heavily impacted by these practices. We also look at the consequences of the policy choice made to respond to drug abuse through mechanisms of law enforcement rather than a public health model and discuss how this decision has affected American society, particularly communities of color.