About 75 percent of the world's poor people live in rural areas, and most of them are involved in farming. Agricultural development in these areas is often constrained by issues of access to appropriate technologies; immense "institutional weaknesses"1; and deep problems with the organization and management of research, education, and extension systems. Many countries and agricultural systems thus remain mired in underdevelopment and face major barriers to the use of knowledge and innovation for development. Despite this, however, there are examples of organizational, technological, institutional, and policy innovations that are transforming agriculture and leading to growth and development. Important lessons can be learned and scaled up from the successes that are occurring, as well as from examining cases that did not work. Fortunately, awareness of the vital role that agriculture plays in development is increasing among policymakers and donors in most countries, in part as a result of the current global food-price crisis and in response to the publication of the 2008 World Development Report, which focuses on agriculture. Agriculture remains crucial to developing countries; it has been observed that GDP growth from agriculture benefits the incomes of poor people two to four times more than GDP growth in other sectors of the economy.