Aims: Greater neighborhood co-ethnic density (living in proximity with people sharing an ethnicity) and being foreign-born each can protect against risky drinking, but little is known about whether these two factors interact. Using a representative sample of Latinos and Asians from California, USA, we investigate main and interactive effects of neighborhood co-ethnic density and nativity status in relation to heavy episodic drinking (HED). Methods: This study uses the California Health Interview Survey (N = 30,203) linked with neighborhood data to investigate associations of co-ethnic density and nativity status with HED. Co-ethnic density was based on matching each respondent's ethnicity to the proportion of residents of the corresponding group in their Census tract. Using weighted logistic regression, we first examined main effects of neighborhood co-ethnic density and respondent nativity status on HED. Next, we assessed the interaction of co-ethnic density and nativity status. Finally, we estimated nativity-stratified models to investigate variation in effects of co-ethnic density. Results: Co-ethnic density was not associated with HED for the full sample, but US-born nativity status was associated with increased odds of past-year HED. The interaction model showed co-ethnic density and nativity had synergistic effects, whereby greater levels of neighborhood co-ethnic density buffered risk associated with being US-born. Further, greater neighborhood co-ethnic density was associated with reduced odds of HED for US-born respondents, but it was not associated with HED for foreign-born respondents. Conclusions: Protective effects of high neighborhood co-ethnic density on HED are stronger for US-born than for foreign-born Latinos and Asians in California.
