A longitudinal study of melanocytic nevi in children born in Colorado in 1998 and followed up from 3 to 8 years of age is presented in this issue of the Archives.1 The authors found that skin phenotype, sex, and body site influenced the development of nevi. The total number of nevi increased linearly during the whole study period in non-Hispanic white, Hispanic white, and Asian/Pacific Islander children, whereas a moderate increase was evident only to 5 years of age in black children. Although the total number of nevi increased by approximately 5 nevi per year in both sexes combined, the number of nevi leveled off in chronically sun-exposed body areas at 5 to 6 years of age in girls and significantly later (at 7 years of age) in boys.1