Three study sites were selected: Indianapolis, Ind.; Newport News, Va.; and Garden Grove, Calif. Interventions proposed for the sites were to develop felony arrest conviction standards, train personnel in new conviction standards, develop and implement felony arrest prefiling screening procedures, and develop and implement mechanisms for feedback on case dispositions between prosecutors and police. The study compared felony case attrition in the posttest period to that in the baseline period, compared case attrition in the experimental groups with attrition in the control groups, examined the influence of misdemeanor filings or convictions on attrition, analyzed prosecutor screening decisions, explored felony case dispositions by type of disposition, and considered the reasons for these case outcomes. Contrary to the central study hypothesis, the amount and quality of physical evidence played a minor role in felony case attrition. The degree and quality of communication between police and prosecutor on felony arrest processing was a major factor in felony case attrition. Obstacles to improving such communication were historically different objectives between the police and prosecutor; institutional inertia; and the short time period between felony arrest and filing with the prosecutors, which tended to produce weak cases. Policy recommendations are a long-term program of planned change in police-prosecutor relations, maintenance and improvement in feedback on arrest outcome from prosecutors to the police, and a new definition of a 'successful' felony arrest built into police performance evaluation. Appended supplementary information and 47-item bibliography.