The SDP promised substantial budgetary increases to New York City's district attorneys if they disposed of their oldest cases. Primary data for assessing the program's impact over 2 years were obtained from interviews with persons working within and outside the criminal courts of the city. Although SDP did not result in a reduction in jail overcrowding, it did succeed in motivating district attorney's to focus on the problem. One lesson learned from the SDP experience is that incentives are more likely to be successful when the perceived size of the reward is high enough to balance the perceived costs of compliance. Policy incentives are more likely to be successful in contexts in which the ability of the policymaker to deliver on promised rewards is perceived to be likely or where the targets of the incentive believe the reward will not be obtained without compliance. The study also develops principles for when to use incentives to achieve reform. 3 tables and 30 notes. For the full report, see NCJ 111513.