Because migration is such a widespread phenomenon, studies of the effects of accompanying life change on the health and well-being of the migrant have special significance in areas like California that support large migrant communities. Previous studies have shown that increased weight and elevated blood pressure may be linked to changes in diet, exercise habits, and the altered sociocultural milieu of the migrant. Among Samoans, a Pacific Island population of Polynesian descent, these changes appear to be particularly prominent in segments of the population that have moved to the environment of Hawaii, which epidemiologic studies have characterized as "intermediate-modern.' Preliminary findings from a survey of weight, height, blood pressure, fasting glucose levels, and mortality records among Samoans living in California indicate that individuals living under more highly urbanized conditions exhibit even more pronounced changes. Adult weight among Samoans in California (San Francisco) greatly exceeds that of their counterparts in Hawaii and Samoa. Elevated blood pressures are also seen, though the extent to which this is associated with excessive weight gain is unclear. The number of individuals with high (greater than or equal to 160 mg/dl) fasting plasma glucose levels would be consistent with a population in which the prevalence of diabetes is many times higher than in the U.S. population. Although mortality patterns are difficult to determine for this population, available records suggest an excess mortality from cardiovascular diseases of all types among adult Samoans under age 50. Further investigations will attempt to link biobehavioral changes in the migrants' lifestyle to these observed patterns of risk.