A cross-sectional study of 38 24-28-y-old Caucasian women was undertaken to identify associations between dietary factors, physical activity (PA), and radial bone measurements during the third decade. Measurements included radial bone mineral content (BMC) and bone density (BD), nutrient intakes, and PA patterns. PA and calcium intake were positively associated by multiple linear-regression analysis whereas protein and phosphorus were negatively associated with radial bone measurements (P < 0.05). Lean body mass was positively associated with mid BMC only (P = 0.0203). No significant effect of age on BD or BMC was observed. We conclude that in this sample of 24-28-y-old women BD and BMC did not differ by age, and behaviors that had a positive impact on radial bone measurements included at least moderate PA and adequate dietary calcium intake, whereas adverse dietary practices for BD included intakes of protein and phosphorus greater than recommended amounts.