The Multi-Country Evaluation of the Integrated Management of Childhood Illness (IMCI) includes studies of the effectiveness, cost, and impact of the IMCI strategy in Bangladesh, Brazil, Peru, Tanzania, and Uganda. Seven questions were addressed when the evaluation was designed: who would be in charge, through what mechanisms IMCI could affect child health, whether the focus would be efficacy or effectiveness, what indicators would be measured, what types of inference would be made, how costs would be incorporated, and what elements would constitute the plan of analysis. We describe how these questions were answered, the challenges encountered in implementing the evaluation, and the 5 study designs. The methodological insights gained can improve future evaluations of public health programs.