The study's objective is to demonstrate the efficacy of a behavioral/educational intervention in increasing levels of dietary calcium intake and weight-bearing exercise within an at-risk population in a stage of rapid accrual of bone mass-specifically, premenarchal girls between the ages of 10 and 12. We will use cluster randomization to randomize girls to either the intervention or a program of education only. We will randomize eighteen groups of girls into each arm of the study.