This is one of a series of seven in-depth country studies on maize production systems in Asia, funded by the International Maize and Wheat Improvement Center (CIMMYT) and the International Fund for Agricultural Development (IFAD). It is part of a project designed to promote sustainable intensification of maize production systems while ensuring equitable income growth and improved food security, especially for poor households that depend on maize. Maize is one of five major crops grown in the uplands of Thailand, along with rice, cassava, sugar cane, and rubber trees. Government-promoted crop diversification, increased population growth, improved transportation networks, inter national trade, expansion of upland farming areas, and increased demand for grains from the domestic livestock and poultry industry stimulated Thailand's maize production beginning in the 1980s. However, Thailand's domestic maize supply is currently not sufficient to meet the needs of its in-country demands, and small quantities have to be imported. Rapid economic growth and accelerated urbanization are expected to create an even higher demand for maize in Thailand. This trend will lead to the intensification of current maize production systems, with more land being shifted to maize production, particularly in marginal areas. Thailand's challenge is to produce more maize for an expanding market, while preserving the natural resource base and the environment through careful agricultural planning. Effective policy design and implementation must be based on comprehensive, accurate data on the current state of maize-based farming systems. This study characterized the social and biophysical maize production environment of Thailand; examined its response to increasing maize demand; determined constraints to future productivity growth; indicated the potential envir onmental consequences, and examined the options available for promoting sustainable growth in maize production.