Our goal was to explore the perceived determinants of obesity in Brazilian, Latin American and Haitian women. This is part of an ongoing community-based participatory intervention. Focus groups by immigrant group were conducted and themes extracted. Women expressed differences in beliefs, attitudes, and barriers regarding diet and physical activity in the US versus their home country. Participants thought food in the US is "less natural," there is less time for preparation, and there is more variety. The weather is a barrier to physical activity in the US and work is more physically demanding. Job-related efforts were not considered physical activity. They reported higher levels of stress, less control of their time and less social support in the US. Providing immigrants with appropriate support and education early in the acculturation process has the potential to help prevent obesity.