Agricultural research and development programs in developing countries and the donor agencies that support them generally allocate more resources to seed programs than to any other aspect of potato improvement. The results have been mixed. Most efforts to establish conventional seed potato certification programs have encountered serious obstacles, both technical and institutional. Few seed certification programs have been able to produce more than a small portion of the seed that farmers need to plant each year. After an initial period of growth, often based on foreign funding and technical assistance, many seed programs have collapsed when foreign support was withdrawn. The Republic of Korea's early attempts at seed certification were no exception to this general rule. However, through persistence, discipline, and application of advanced techniques for in vitro multiplication and virus testing of potatoes, Korea's Seed Potato Certification Program has become a remarkable success. This report summarizes the main features of the Korean experience; it outlines the seed program's technical and institutional arrangements; it indicates the magnitude of the program's costs and benefits; and it identifies some important issues that still face the program's managers. A central conclusion is that the seed program's impact, stemming primarily from technical innovation, could now be extended by turning greater responsibility for seed production over to the private sector and by expanding efforts in the areas of breeding, postharvest technology, and on-farm research.