The paper has several specific objectives. First, it identifies how fertilizer marketing costs and the types of fertilizers used have changed over the course of the liberalization process in Kenya. A second objective is to examine the fertilizer subsector in Kenya with a view to identifying organizational and institutional changes that could improve its performance. Various types of fertilizer supply chains serving farmers in western Kenya are identified, examine the cost structure of these supply chains, identify potential sources of cost reduction in these supply chains, and last, estimate the impact of illustrative scenarios for reducing fertilizer marketing costs on the profitability of maize production in western Kenya.