The objective of this paper is to review progress made and challenges remaining as Sahelian governments and entrepreneurs work together to develop the input markets that are so essential to the modernization of Sahelian agriculture. The paper is designed to inform Sahelian decision makers. Because the most important purchased input in the Sahel is currently inorganic fertilizer, the paper focuses on fertilizer markets. In an effort to provide Sahelian decision makers with information on a broad range of options, we have drawn on experiences throughout W. Africa rather than focusing only on the Sahel. Numerous references to experiences in the Coastal countries of W. Africa not only provide Sahelians with some perspective on how their experience compares to that of other W. African countries, but also contribute to an understanding of the opportunities and constraints to developing regional input markets. Developing input markets is a major challenge throughout Africa, not just in the Sahel.