Introduction: Excess visceral fat is implicated in obesity-related cardiometabolic disease, but normal age, sex, and ancestry-related trends in visceral fat among youth with varying body size and metabolic health status are unknown. Objective: The objective of this study was to characterize age, sex, and ancestry-related trends in abdominal visceral fat among youth with healthy weight, obesity, and type 2 diabetes. Methods: This cross-sectional sample included youth ages 10 to 23 years (67% female, 56% non-black) with healthy weight (BMI=5 th to 85 th percentile, n=236), obesity (BMI > 95 th percentile, n=224), and type 2 diabetes (BMI > 95 th percentile, n=145). Visceral fat (cm 2 ) was assessed via dual-energy X-ray absorptiometry. Multiple linear regression analyses were performed to examine interaction and main effects of age, sex, and ancestry in relation to visceral fat (log) in the three groups separately. Results: Age was positively associated with visceral fat in the healthy weight (P<0.001), obese (P<0.001), and type 2 diabetes groups (P=0.051), such that visceral fat was greater in later adolescents and young adults compared to younger children. Non-blacks had significantly greater visceral fat compared to blacks in the healthy weight (P=0.003), obesity (P<0.001), and type 2 diabetes groups (P<0.001). Sex differences in visceral fat differed by group. In the healthy weight group, males had significantly greater visceral fat than females, but in the obesity group, females had greater visceral fat than males (both P<0.001). In the type 2 diabetes group, females tended to have greater visceral fat, but this difference did not reach statistical significance (P=0.060). When accounting for BMI, significant sex and ancestry differences were maintained, but age associations were nullified. Conclusions: This study reports novel findings with respect to demographic determinants of visceral fat assessed via DXA in children, adolescents, and young adults. Our findings that sex differences in visceral fat in youth with obesity and type 2 diabetes persisted following control for BMI are novel and of clinical interest. Specifically, that females may accrue greater visceral adiposity with weight gain when compared to their male counterparts might help to explain differing risk for obesity-related chronic disease. Prospective studies of youth during critical periods of growth are needed to define the consequences of excess visceral fat accrual with respect to future cardiometabolic risk.