This paper attempts to contribute towards an understanding of population mobility by thoroughly studying population mobility in 5 villages in North Kelantan, Malaysia. The region is one in which outmigration is of much demographic, economic, and social significance. An analysis of the data on previous place of residence collected in the 1970 Census shows that 5 of the 6 districts of North Kelantan had net migration rates greater than -10, amongst the highest rates of outmigration in Peninsular Malaysia. Types of mobility range from daily commuting through the seasonal migration of harvest workers and the circular migration of urban laborers to the relatively permanent migration of well-educated villagers to urban employment and the less-educated to settle land. The paper describes the main types of mobility identified in the survey villages, evaluates the income earned through mobility, discusses some of the broader socioeconomic effects of mobility, and attempts to identify some of the implications of the material presented. Population mobility is not new in Kelantan, but the scale, direction, and character of movement has changed in response to political conditions, increasing pressure on land resources, the uneven regional development, and capitalist penetration of Malay during and after the colonial period, improvements in transportation, and the spread of education. The movement of people from Kelantan in search of temporary work elsewhere in Malaysia appears to have increased since the 1930s. During and after World War II, the movement of laborers to harvest rice in Kedah and Perlis became a regular seasonal migration. In recent years, this seasonal migration to Kedah and Perlis has declined markedly. In the survey only from 0-15% of households in each village had a member who had work in those states in the past 12 months, with an average for 5 villages of 3%. The movement of men to work as laborers on building and construction sites in Singapore is now the predominant type of circular migration in the 5 survey villages. Other types of temporary or circular migration at present include work on plantations, rubber tapping, and temporary cultivation of land. Income resulting from mobility is a major contributor to the economy of some households in North Kelantan and a useful supplement for many others. It also is an outlet for a proportion of rural youth who have been educated out of agriculture but not into alternative, full-time occupations. The net benefits to the rural economy as a whole resulting from mobility are relatively small, as the flow of income into village households is balanced by a related flow of income and resources out of the rural area, most of the income gained from mobility is spent on consumption rather than investment, and migration does not seem to have led to any significant innovation. On the whole, mobility has helped to maintain the village economy in the face of increasing rural pressures.