Sustained high rates of growth in sales of certified organic products (OPs) in the U.S. and worldwide, averaging 20-25% yr(-1) since 1990, have spurred concomitant growth and activities in production, processing, research, regulation and trade agreements, and exports. The global OP market value in 2001 is estimated to be $20B, and the OP share of total food sales is near 2% in the US and 1-5% in EU countries. Processed OPs have shown particularly rapid growth, often over 100% yr(-1). Commercial certified organic agriculture (OA) has spread to over 130 countries worldwide. Demand for OPs is driven by belief that OPs are more healthful, tasty, and environmentally friendly than conventional products (CPs). Evidence for these beliefs is reviewed. While many of the health claims for OPs remain unresolved, there is sufficient evidence to give OPs the edge in healthfulness. Comparative research is needed, particularly bioassays on animals and analyses of the functional components of foods (nutraceuticals). OP/CP taste comparisons are often inconclusive. Evidence for significant environmental amelioration via conversion to OA is very substantial-pesticides are virtually eliminated and nutrient pollution substantially reduced loss of biodiversity, wind and water erosion, and fossil fuel use and greenhouse warming potential are all reduced in OA relative to comparable conventional agriculture (CA) systems. The agroecological characteristics of OA are reviewed-weed, invertebrate, disease, and soil fertility management practices. Yield reductions of OA systems relative to CA average 10-15%, however these are generally compensated for by lower input costs and higher gross margins. Large-scale conversion to OA would not result in food shortages and could be accomplished with a reduction in meat consumption. OA systems consistently outperform CA in drought situations, out-yielding CA by up to 100%. Also reviewed are: methodologies for comparing productivity and sustainability of OA/CA; the core concept that OA is a structurally different system than CA; the characteristics, sociology, and practices of US organic farmers and farms; OA's origins, its pioneers, major institutions; international certification standards and the new (2000) USDA National Organic Program Final Rule; institutional and media support for and biases against OA; OA's increased involvement with social accountability and animal ethics.