Clustering of long-term rates of change in metabolic syndrome variables (body mass index, homeostasis model assessment of insulin resistance, ratio of triglycerides to high-density lipoprotein cholesterol, and mean arterial pressure) from childhood to adulthood was evaluated longitudinally (1982-2003) in a cohort of 389 Blacks and 631 Whites who were examined 3-6 times both as children (ages 4-17 years) and as adults (ages 18-38 years) over an average of 16 years (3,874 observations). The incremental area under the growth curve was used as a measure of long-term rates of change in risk variables since childhood. Intraclass correlations, a measure of the degree of clustering, among the four variables were significant (p < 0.001) for childhood, adulthood, and incremental area values and were higher in adulthood than in childhood. Blacks showed a higher degree of clustering of long-term rates of change in risk variables than did Whites. Adjustment for body mass index reduced the degree of clustering by approximately 50%. These results show that metabolic syndrome variables coexist in terms not only of their levels in childhood and adulthood but also of long-term rates of change. Obesity is of critical importance in the development of metabolic syndrome, and its prevention beginning in childhood needs to be addressed.