This study is concerned with blood pressure behavior in young adults (aged 15 to 29 years) in the biracial community of Evans County, Ga., on two occasions 7 years apart. On the basis of casual blood pressure recordings the prevalence of systolic pressure equal to or greater than 140 mm Hg or diastolic pressure equal to or greater than 90 mm Hg, or both, showed race/sex differences as follows: white males 19.0 percent, white females 12.7 percent. black males 34.0 percent, black females 31.6 percent. Similar differences were noted in the incidence during the 7 year interval. The problem presented by the variability of the casual blood pressure recording is apparent in this interval study. Of particular interest is the association of weight with blood pressure in this youthful group, particularly among white males and females and black females, in relation to both initial and subsequent pressure levels. The data suggest that in this population under 30 years, weight is a risk factor for hypertension, and that maintenance of ideal weight, instituted in youth, may be a preventive measure.