Near the end of 1999, teams of independent evaluators were appointed by the Home Office Policing and Reducing Crime Unit to assess the TPI's funded under the Crime Reduction Programme. TPI programs focus on implementing the concepts of problem-oriented policing in countering various types of crime problems in a police jurisdiction. The tasks of the evaluators was to identify what works, where, and most cost effectively. This chapter focuses on the cost-effectiveness analyses used by the authors' evaluation team. Cost-effectiveness analysis has three basic stages: identifying, measuring, and valuing resources used; identifying and measuring outputs and outcomes; and relating these two stages to derive cost-effectiveness estimates. This chapter illustrates the first two stages by referring to all five TPI projects. A case study that compares the two TPI's that targeted vehicle crime is used to clarify the assessment of cost-effectiveness. The other sections of the chapter analyze the various demands of cost-benefit analysis and its potential for future use. The authors recommend where economic evaluation, notably cost-effectiveness analysis, can contribute to resource allocation in the context of problem-oriented policing. Their general advice is that the use of economic evaluation techniques, such as cost-effectiveness analysis, will not produce significant benefits unless the purpose and value of linking outputs/outcomes to costs are more widely appreciated and the results of such analyses are disseminated. Some of the lessons drawn from undertaking large-scale, real-time cost-effectiveness and cost-benefit analyses include agreeing on project scope and objectives while taking into account project evolution; development of a mutual understanding of evaluation requirements in advance of project planning; identification of the range of potential outputs and outcomes and defining of appropriate measures; and carefully distinguishing what is specific to a particular project and what is more generic. 7 tables, 2 notes, and 12 references