Bone area (BA) and bone mineral content (BMC) were measured from childhood to young adulthood at the total body (TB), lumbar spine (LS), total hip (TH), and femoral neck (FN). BA and BMC values were expressed as a percentage of young-adult values to determine if and when values reached a plateau. Data were aligned on biological ages [years from peak height velocity (PHV)] to control for maturity. TB BA increased significantly from −4 to +4 years from PHV, with TB BMC reaching a plateau, on average, 2 years later at +6 years from PHV (equates to 18 and 20 years of age in girls and boys, respectively). LS BA increased significantly from −4 years from PHV to +3 years from PHV, whereas LS BMC increased until +4 from PHV. FN BA increased between −4 and +1 years from PHV, with FN BMC reaching a plateau, on average, 1 year later at +2 years from PHV. In the circumpubertal years (−2 to +2 years from PHV):​ 39% of the young-adult BMC was accrued at the TB in both males and females;​ 43% and 46% was accrued in males and females at the LS and TH, respectively;​ 33% (males and females) was accrued at the FN. In summary, we provide strong evidence that BA plateaus 1 to 2 years earlier than BMC. Depending on the skeletal site, peak bone mass occurs by the end of the second or early in the third decade of life. The data substantiate the importance of the circumpubertal years for accruing bone mineral.