Given the growing population of Latino immigrants in the United States, it is critical for counselors to understand pre- and postimmigration social contextual factors affecting the mental health of this heterogeneous ethnic population. The objective of our cross-sectional, retrospective study was to investigate the potential protective influence of preimmigration family cohesion on drug/alcohol abuse just prior to migration among 527 Latino young adults (age 18-34 years). Multivariate Poisson regression indicated that preimmigration family cohesion was inversely related with harmful/hazardous alcohol consumption, the frequency/quantity of alcohol use, and illicit drug use when controlling for the potentially confounding sociodemographic factors of gender, age, education, income, marital status, and immigration status (documented or undocumented). Associations between family cohesion and drug/alcohol use behaviors varied between Central American immigrants and Caribbean/South American regional groups. Preimmigration findings offer a fuller contextual understanding of the lives of Latino young adult immigrants and support the importance of family cohesion as a buffer against drug/alcohol abuse. (Contains 3 tables.)