Our knowledge base regarding bone formation in adolescence is incomplete. The following research question addresses the specific aim: What effects will dose-dependent rope jumping have on total body (TB), lumbar spine (LS), femoral neck (FN), and greater trochanter (GT) bone formation of postpubescent girls? The study was a randomized control trial to test the effectiveness of a jump rope intervention to increase bone mass in high school girls. Upon study entry, girls were randomly assigned to either one of two treatment groups (high volume, HV; low volume, LV) or a control group. Thirty-seven high school girls (aged 14.7 + 0.7; 24.2 + 10.8 months past menarche) were recruited to participate in the study (LV, N=12; HV, N=13, control, N=12). DXA measurements of TB, proximal femur (FN and GT) and LS (L2-4) BMC were acquired at baseline and at follow-up four months later and analyzed on a Lunar DPX-L densitometer (Lunar Corp., Madison, WI). All intervention participants jumped or stretched four times per week at the beginning of their regular physical education classes. The HV and LV students jumped rope at a rate of 50 jumps per minute for 10 and 5 min respectively. The LV students stretched for 5 min after jumping. The jumping pace was controlled by the use a metronome. Over time, participants from both intervention groups added weighted vests and progressively added weight to maintain overload. The control group walked for 5 min and then stretched for 5 min at the beginning of class. The mixed model ANCOVA of FN and GT BMC revealed a significant difference between conditions (p=.041, p=.011 respectively). Bonferroni pair wise comparison revealed a significant difference between the HV and control conditions. The general conclusion concerning this investigation was that the 10 min jump rope intervention increased FN and GT BMC more than the control condition in postpubescent girls. Although difference were not significant a dose response was evident, the 10 min jump rope intervention produced greater gains in TB (HV: 2.25%, LV: 1.59%, Control: 1.03%), LS (HV: 2.43%, LV: 2.02%, Control: 1.15%), FN (HV: 4.41%, LV: 2.98%, Control: 1.64%), and GT (HV: 5.01%, LV: 3.87%, Control: 1.94%) BMC than 5 min jump rope intervention and this trend was demonstrated between the 5 min jump rope condition and the control condition. Keyword(s): exercise/fitness, health promotion, research