Background: Research examining alcohol use trajectories among Latina/os is scarce. Further, prior findings on alcohol use by ethnic group and gender is mixed. The purpose of this study was twofold. First, to examine developmental trajectories for two types of alcohol (drunkenness and heavy drinking) use across four Latina/o ethnic groups (Cubans, Puerto Ricans, Central/South American, and Mexican Americans). Second, to examine the role of gender and ethnicity in developmental trajectories of drunkenness and heavy drinking among Latina/os. Methods: Data were drawn from Waves I-IV of the National Longitudinal Study of Adolescent to Adult Health. The sample consisted of 1670 Latina/os that were followed from adolescence into adulthood. Multi-level logistic regression models were used to estimate drunkenness and heavy drinking trajectories and trajectories by gender. Results: Results indicate that, for all four ethnic groups examined, the probability of drunkenness and heavy drinking gradually increased in adolescence, peaked in “emerging adulthood”, and decreased as they transitioned into adulthood. Findings also show divergent age trajectories by gender, but patterns varied across ethnicity and alcohol use outcome. Conclusions: Key findings from this study demonstrate that among Latina/os, there are critical developmental periods for reported drunkenness and heavy drinking in the last 12 months, and that ethnicity and gender play substantial roles in the development of hazardous alcohol use over the life course.