Despite substantial heritability in pubertal development, children differ in maturational tempo.(i) puberty and its duration are influenced by early changes in height and adiposity. (ii) Adiposity rebound (AR) is a marker for pubertal tempo.We utilized published prospective data from 659 girls and 706 boys of the Study of Early Child Care and Youth Development. We investigated the age of pubarche-thelarche-gonadarche-menarche as a function of early height, BMI, and AR.In girls, height standard deviation scores correlated negatively with thelarche and pubarche from 15 mo of age and with menarche from 54 mo. BMI correlated negatively with thelarche from 36 mo of age and menarche from 54 mo. In boys, age at gonadarche correlated negatively with height from 36 mo of age. An AR was detected in 47% of girls and 55% of boys, who became heavier and had earlier and faster puberty than those with no AR.The onset and tempo of puberty are influenced by a two-hit program. The first is exerted during the infancy-childhood transition (ICT; 6-12 mo) and includes height, as an early predictor of maturational tempo. The second hit occurs at the childhood-juvenility transition (5-7 y) and is based on adiposity and its rebound.