Watson, Crawford, and Farley examine the ways in which science and technology (S&T) support poverty alleviation and economic development and how these themes have been given emphasis or short shrift in various areas of the World Bank's work. Central to their thesis is the now well-established argument that development will increasingly depend on a country's ability to understand, interpret, select, adapt, use, transmit, diffuse, produce, and commercialize scientific and technological knowledge in ways appropriate to its culture, aspirations, and level of development. The authors go beyond this tenet, analyzing the importance of S&T for development within specific sectors. They present policy options for enhancing the effectiveness of S&T systems in developing countries, review previous experience of the World Bank and other donors in supporting S&T, and suggest changes that the World Bank and its partners can adopt to increase the impact of the work currently undertaken in S&T. The authors' main messages are: 1) S&T has always been important for development, but the unprecedented pace of advancement of scientific knowledge is rapidly creating new opportunities for and threats to development. 2) Most developing countries are largely unprepared to deal with the changes that S&T advancement will bring. 3) The World Bank's numerous actions in various domains of S&T could be more effective in producing the needed capacity improvements in client countries. 4) The World Bank could have a greater impact if it paid increased attention to S&T in education, health, rural development, private sector development, and the environment. The strategy emphasizes four S&T policy areas: education and human resources development, the private sector, the public sector, and information communications technologies.