In many developing countries the composition of rural households is influenced by the migration of adult household members to urban locations in search of employment. Children may be left in the care of their mother alone, or in the care of grandparents when both parents have migrated. Using representative data from a household survey conducted in rural Northeast Thailand in 2003, this paper investigates whether household composition has any effect on the welfare of children, as measured by anthropometric measurements including height-for-age, weight-for-age, and weight-for-height. Our findings suggest that household types other than nuclear families result in some significantly worse child nutritional outcomes. The implication is that governments should protect the welfare of the children of migrants, either through targeted programs or through increased opportunities for employment in rural areas.