The Operant Model of Acculturation predicts that health behaviors that have a low prevalence (< 20%) among Traditional (low-acculturated) minorities increase in prevalence with acculturation and hence have a higher prevalence among their Acculturated counterparts. Alternatively, health behaviors that have a high prevalence (> 45%) among Traditional minorities decrease with acculturation and thereby have a lower prevalence among their acculturated cohorts. The purpose of this study was to test this model for the first time. Data on the 7,249 Mexican American adults in the 2001 California Health Interview Survey (CHIS), a statewide, random-digit-dial telephone survey, were used. Two proxies for acculturation (nativity, language spoken at home) were predictors in analyses of cigarette smoking, exercise, and 5 + daily fruit/vegetable consumption. For all three health behaviors, results were fully supportive of the Operant Model irrespective of acculturation-proxy and demographic variables. The Operant Model may provide a coherent framework for predicting and understanding the role of acculturation in ethnic minority health behavior. Findings are discussed in terms of tailoring and targeting interventions in a manner consistent with the acculturation-related changes in health behavior that are likely to occur.