The facts that black Americans at all ages have higher blood pressure levels and higher mortality rates from hypertension than whites provided the impetus for this study. In their efforts to discover whether the level of blood pressure within and between black and white groups is related more to stress or to genetic factors, the researchers collected data about health, blood pressure, and perceived life-stress from a Detroit area sample of blacks and whites who live in either high stress or low stress areas of the city. Major hypotheses dealt with the relation of blood pressure to socioecological and medical factors, sociopsychological factors, and heredity. Numerous results are presented which suggest hypothesized relationships with all 3 factors. (TL)