This article, the second of a two-part series, describes approaches to evaluate interventions for prevention and control of infectious diseases. Evaluation should take place at all stages in the development and application of such interventions, whether preventive or therapeutic. At least four different types of evaluation can be carried out: developmental evaluation, relevance evaluation, process (administrative) evaluation, and impact evaluation. For therapeutic interventions, cure is the best indicator of effectiveness. For preventive interventions, reduction in the occurrence of the condition is the best measure of effectiveness. However, process and administrative evaluation and economic evaluation also play important roles.