Context: Violence among U.S. Hispanic adolescents is a significant public health problem. All Hispanics undergo the process of acculturation when adapting to life in the United States, but little is known about how acculturation affects their risk of violence. Lengthy acculturation scales are rarely available in national, population-based surveys, and single-item, proxy measures may not accurately capture the process of acculturation. Objectives: This research was conducted to accomplish two main objectives: 1) the validation of a proxy acculturation scale, and 2) the quantification of the association between acculturation level and interpersonal and intrapersonal violence. Methods: The validation analysis utilized the 1984 National Alcohol Survey (NAS), a nationally representative survey which included 1,437 U.S. Hispanic adults, to validate a proxy acculturation scale. The NAS acculturation scale was used as the gold standard against which the proxy scale was compared. The associational analyses were conducted using data from the first two waves of the National Longitudinal Survey of Adolescent Health administered in 1995 and 1996. This dataset included a nationally representative, school-based sample of 2,298 U.S. Hispanic/Latino adolescents in grades 7 through 12. The associations between the exposure (acculturation level as measured by a 3-item proxy scale) and the outcomes (fighting, fight-related injury, suicidal ideation, and suicide attempt) were evaluated. Results: The proxy acculturation scale had good internal reliability and good validity. The measure had better validity among adolescents of Mexican, Puerto Rican and Cuban heritage compared with those reporting other countries of origin. The odds of reporting a violent outcome were higher among U.S. Hispanic/Latino adolescents of moderate-to-high acculturation compared with those of low acculturation. The elevated risk remained after controlling for confounding. Effect modification by gender and country of origin was suggested. Conclusions: The PAS3 is a valid tool for measuring acculturation when use of a comprehensive acculturation scale is not feasible. U.S. Hispanic/Latino adolescents of moderate-to-high acculturation are at increased risk of violence compared with their less acculturated counterparts. The heterogeneity of the Hispanic population as well as acculturation level must be considered when designing and implementing violence research and prevention programs.