Purpose: Eliminating health disparities among ethnic groups is one of the overreaching goals of both the World Health Organization and Healthy People 2010. Limited empirical evidence exists on the prevalence of adolescent overweight and physical activity in island territories and nations such as Guam and Palau. The primary objectives of the study were to determine the prevalence of overweight and physical activity, and compare values to US counterparts. Methods: A total of 323 (192 Guamanian, 131 Palauan) in grades 6-8 participated in the study and provided written informed consent and assent. Participants wore sealed pedometers for 8 weekdays and physical activity was expressed as mean steps/day. Body Mass Index (BMI) was determined from directly measured height and weight values. Participants were classified as normal, at-risk for overweight, or overweight using CDC BMI-for-age growth charts to obtain percentile ranking. Greater than or equal to the 95th percentile of BMI for each age and sex group was used to classify overweight participants. Analysis/Results: Guamanian (M 8537, SD 2698) and Palauan Boys (M 10800, SD 3167) accumulated approximately 1,200 (14%) and 2,800 (26%) more (p<.01) steps/day than their Guamanian (M 7369, SD 2343) and Palauan girl (M 8000, SD 2967) counterparts, respectively. Twenty percent of Guamanian and 26% of Palauan adolescents were classified as overweight. Conclusions: Guamanian and Palauan adolescents accumulated approximately 2,000-5,000 fewer steps/day than the U.S. counterparts. Similar to all other ethnic groups, girls were less active than boys. Disparities between sexes in the Palauan group were larger (24% fewer steps/day) than disparities between sexes in predominately white adolescents (5-19% fewer steps/day). Compared to other groups of adolescents from NHANES '00-'02 data that used directly measured height and weight values to determine overweight status, the prevalence of overweight in Guamanians (20%) exceeded Whites (14%) by 6 percentage points, but was lower than Mexican-Americans (23%) by 3 percentage points and Non-Hispanic Blacks (21%) by 1 percentage point. The prevalence of overweight in the Palauan group was higher than all US groups. Specifically, Palauans exceeded Mexican-Americans (23%) by 3 percentage points and Non-Hispanic Blacks (21%) by 5 percentage points, and nearly doubled the prevalence in Whites (14%). Interventions are needed to reduce the prevalence of overweight and increase the prevalence of physical activity in these underrepresented island populations. Keyword(s): international issues, multiculturalism/cultural diversity, obesity issues