Among migrant workers (MWs) in the US, HIV/AIDS prevalence may be as high as 13.5%. This serial cross-sectional study examines associations between Ethnic Identity (EI) in African American and Hispanic MWs and short-term changes in high-risk sexual behaviors. Baseline and 3-month follow-up data was collected from a larger HIV intervention study among MWs in Immokalee, Florida (n = 119) who reported unprotected sex in the past 30 days. The Multigroup Identity Measure was used to assess EI. A high EI score indicates less acculturation to one's new surroundings. Females had higher levels of positive behavior change. Lower EI was associated with higher levels of positive change in relation to HIV/AIDS risk behavior. Among Hispanics, education was negatively correlated with EI. Education was a predictor of behavior change. Future interventions should focus on reducing acculturation stress, which may prompt harmful coping behaviors, such as high-risk sex and substance abuse.