Abstract
Evaluation research involves the use of the scientific method to evaluate the impact of public programs. The cross-disciplinary evaluation research literature provides a useful orientation for the examination of activities of international organizations. The primary advantage of this approach is that more dependable cause and effect statements are possible. The major limitations relate to its applicability, vary from case to case, and should not be underestimated. Yet they do not preclude its beneficial use by international organization scholars and policy makers. The smallpox eradication program of the World Health Organization serves as the basis for an illustration of the evaluation research methodology.