Data from Project Heartbeat were analyzed. Hypotheses tested included: (1) the time patterns of change in several indicators of body size, composition and configuration over the period of observation; (2) the relations between the time patterns of change in these indicators and the corresponding patterns for change in selected endocrine factors; and (3) the explanatory contributions of energy intake and expenditure to variation between individuals in their observed time patterns of change in these indicators. The anthropometric indicators addressed were: weight (total mass), height, body mass index (BMI, wt/ht2), fat-free mass, fat mass, per cent body fat, and fat distribution (waist/hip ratio). Each of these indicators were examined first separately and then in relation to selected endocrinologic measures (testosterone, estradiol, and DHEAS) and to energy intake and expenditure (from interview histories of diet and physical activity). Existing data from up to twelve 4-monthly examinations over the age range from 8-17 years conducted in Project HeartBeat! were analyzed.