Dual energy x ray absorptiometry (DEXA) has been shown to be an effective measure of body composition and is considered the “gold standard” of body composition measurement. Body mass index (BMI) has been used as the measure of choice for the Centers for Disease Control and Prevention, yet there has been some controversy as to the predictive utility of this measure. Bioelectrical impedance (BIA) and skinfold (SF) measurement have been used as body composition measures by many labs and private facilities as a means to improve the health of participants. PURPOSE: The purpose of the study was to examine the efficacy of BMI, BIA and SF in predicting body composition when compared to DEXA. Researchers examined four accepted methods of measuring body composition: BMI, calibrated Hologic 4500W dual energy x ray absorptiometry (DEXA), SF using a standard 3-site body composition assessment, and BIA using Xitron 4200 Bioelectrical Impedance Analyzer (San Diego, CA) which measures bio resistance of water and body tissues based on a minute low energy, high frequency current transmitted through the body. All four methods were evaluated using a cohort of students who have been sedentary for at least the past three months. METHODS: A convenience sample of sedentary college aged students (N=101) from Health and Human Behavior classes at a southern university were chosen to participate in a 12-week behavior change study. Body composition measures were obtained to investigate the relationship between the four measures and to study the utility of BMI, BIA, and SF. All measures were obtained by trained technicians with proficiency in each of the body composition measures. RESULTS: Pearson correlations for each comparison were .824 for DEXA and SF, .798 for DEXA and BIA, and .551 for DEXA and BMI. All correlations were significant to 0.001. Stepwise multiple regression revealed SF as the greatest predictor of DEXA with 67.5% of variance explained (r2=.675) followed by BIA (12.1%) and BMI (2.6%). Total variance explained was 82.2% (r2=.822). CONCLUSIONS: BMI has been used as means of predicting health, but has been questioned as a measure in healthy weight-trained populations. This study demonstrates less efficacy when compared to DEXA for sedentary populations as well. These findings suggest that BMI may not be as effective a measure as SF or BIA when compared to DEXA and should only be used when SF and BIA are not feasible. Additional comparisons should include a four-compartment method.