||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. 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; investigated the potential environmental consequences, and examined the options available for promoting sustainable growth in maize production. Maize is the second most important food crop in Vietnam after rice. It is the substitute staple in periods of rice shortage, especially for people in rural areas and mountainous regions. Maize is also the primary source of feed for Vietnam’s poultry and livestock industry, and is therefore an important source of income for many farmers. Maize production has risen sharply since 1990, when the Vietnamese government began to strongly support and promote maize hybrid technology. Vietnamese farmers have widely adopted higher-yielding hybrid maize varieties. This was a timely response to Vietnam’s growing livestock and poultry industry, which in turn generates an increasing demand for more maize to use as feed. Rapid economic growth and accelerated urbanization are expected to create an even higher demand for maize in Vietnam. This trend will lead to the intensification of current maize production systems, with more land being shifted to maize production, particularly in marginal areas. Vietnam’s challenge is to provide more maize for an expanding market, while preserving the natural resource base and the environment through careful agricultural planning. Ef fective policy design and implementation must be based on comprehensive, accurate data on the current state of maize-based farming systems.