OBJECTIVE To examine whether measures of neighbourhood economic deprivation, social disorganisation, and acculturation explain homicide mortality differentials between Mexican Americans, non-Hispanic black Americans, and non-Hispanic white Americans, net of individual factors. METHODS Prospective study, National Health Interview Survey (1986-1994) linked to subsequent mortality in the National Death Index (1986-1997). METHODS United States of America. METHODS A nationally representative sample of non-institutionalised Mexican Americans, non-Hispanic black Americans, and non-Hispanic white Americans, aged 18-50 at the point of interview. METHODS Cox proportional hazard models estimate the risk of death associated with various neighbourhood and individual factors. RESULTS Both individual and neighbourhood risk factors partially account for race/ethnic disparities in homicide. Homicide mortality risks are between 20% and 50% higher for residents of areas that have economic inequality of 0.50 or greater based on the coefficient of variation, or where 4% or more of the residents are Mexican American, 10% or more of the residents are non-Hispanic black, or 20% or more of the households are headed by single parents (p< or = 0.05). But residents of areas where 10% or more of their neighbours are foreign born have 35% lower mortality risks than people living in areas with fewer foreign born people (p< or =0.05). These differences persist even after controlling for individual level risk factors. CONCLUSIONS The findings support economic deprivation, social disorganisation, and acculturation theories, and suggest that both neighbourhood and individual risk factors affect race/ethnic differences in homicide mortality. Public health policies must focus on both individual and neighbourhood factors to reduce homicide risks in vulnerable populations.