Overweight and obesity are linked to certain types of cancers and Hispanics/Latinos-the largest ethnic minority group in the United States-are disproportionately affected by obesity. Diet, physical activity, and body image are three factors that influence obesity. Unfortunately, the diets of many Latinos tend to be unhealthy, Latinos have low levels of physical activity, and Latinos hold a general cultural value favoring a degree of overweight-all factors that may increase rates of obesity. Although ethnic and racial differences in correlates of obesity have been examined, little research has been conducted to understand the factors that underlie these differences. This kind of research is important because racial categories and phenotypic characteristics exhibit more within-group than between-group variation. Recently, replacing the word `race'as an explanatory construct in research with conceptual variables such as ethnic identity has also been emphasized, placing more emphasis on cultural aspects of this construct. The purpose of this cross-sectional study is to explore the role of four cultural variables (acculturation, acculturative stress, ethnic identity, and cultural values) that may help to explain the ethnic disparities in correlates of obesity (diet, physical activity, and body image) among Mexican and Puerto Rican women. Specific aims are to: 1) Explore the role of acculturation in diet, physical activity, and body image in 176 adult female Mexicans and Puerto Ricans;2) Explore the role of acculturative stress in diet, physical activity, and body image in Mexicans and Puerto Ricans;3) Explore the role of ethnic identity in diet, physical activity, and body image in Mexicans and Puerto Ricans;4) Explore the relationships between Latino cultural values and diet, physical activity, and body image;and 5) Identify logistical/practical, and cultural considerations regarding the development of culturally proficient obesity interventions for Mexicans and Puerto Ricans. The rationale for this study derives from the PEN-3 Model (Airhihenbuwa, 1995, as well as models on cultural proficiency and tailoring8,9, and community participatory research10,11. The PEN-3 theoretical model emphasizes culture as the central reason for health behavior and the primary consideration for health promotion programs. Culturally proficient research emphasizes the role of culture on affect, thoughts, and behaviors and encourages active community involvement. The findings from this study will aid in understanding the role of ethnicity and culture in obesity-related variables and identify cultural factors to consider when developing obesity interventions for Mexicans and Puerto Ricans. This project will position the PI to apply for future federal research funding. Pilot data from this project will be used to develop and implement a culture-based, community participatory obesity intervention for Mexican and Puerto Rican females. The future R01 grant application will incorporate role of acculturation, acculturative stress, ethnic identity, and cultural values into a diet, physical activity, and body image intervention for Mexican and Puerto Rican females. Therefore, the findings from this present R21 grant application are a necessary and critical component to understanding the independent and interactive influences of Latino cultural variables and their relationship to correlates of obesity. Public Health Relevance: This research is important because it will enable the exploration of four cultural variables (acculturation, acculturative stress, ethnic identity, and cultural values) and their relationship to diet, physical activity, and body image in overweight Mexican and Puerto Rican women. Pilot data from this project will be used to develop and implement a culture-based diet, physical activity, and body image intervention for overweight Mexican and Puerto Rican women that will incorporate the role of acculturation level and the stress associated with the acculturation process, ethnic identity, and Latino cultural values.