The purpose of this review is to summarize the effects of calcium intake on peak bone mass (PBM) accrual by premenopausal females during their 20s and possibly 30s. Prospective studies are highlighted because of the value of investigating the same subjects for one or more years. Results of cross-sectional studies are also summarized. Findings from both prospective and cross-sectional investigations suggest a positive benefit of adequate or supplemented calcium intakes on bone mineral content (BMC) in females during the third (20s) and fourth (30s) decades of life. PBM of subjects was found to be increased or maintained in comparison to PBM of controls in the five intervention studies that used calcium supplementation or the addition of calcium-rich foods. The results of cross-sectional studies, including a meta-analysis of approximately 20 such studies, also support the benefit to PBM of adequate calcium intakes. In summary, sufficient consumption of calcium during the various stages of the early life cycle, when combined with overall sound nutrition, regular physical activity, and possibly pregnancy, lactation, and child-rearing, may contribute to PBM accrual of women during the early adult decades.