Following a historical agreement on the EU enlargement, 10 new member states (NMS) acceded to the European Union on May 1, 2004. Although the European Union has expanded its membership in the past, this enlargement is unique in terms of its scope and diversity of the countries, area, and population involved. Thus, the effects of the EU enlargement on current and future member countries and on world commodity markets require careful consideration as the European Union is a major player in these markets. We analyze the effects of the Common Agricultural Policy (CAP) reform and enlargement on the EU-15, the NMS, and world agricultural markets. We compare three 10-year comprehensive agricultural outlook scenarios. In a “pre-enlargement” scenario, all pre-enlargement policies of the EU-15 are held in place and the 10 NMS maintain their independent economic policies and older technologies as if nothing happens. The second scenario considers the CAP reform in the EU-15. The third scenario is the 2004 Food and Agricultural Policy Research Institute (FAPRI) baseline projection, which incorporates both the CAP reforms and accession of the 10 NMS with the associated domestic and trade policy reforms and some convergence in technology within the EU-25. With prices in most commodities in the acceding countries historically below EU-15 prices, accession leads to a moderate decrease in the EU-15 prices, whereas for the 10 NMS, domestic prices of many commodities increase substantially. Holding income levels constant, consumption levels of agricultural products in these countries decrease in most instances because of higher food prices, while production levels rise. The impact of the two reforms on world markets is moderate to negligible. The CAP reform has a moderate impact on the EU-15.