How does level of acculturation affect the probability that Mexican Americans use general health, mental health, and human social services? We studied this question using data from a general population sample of Mexican Americans (N = 1,055). Data were elicited in face-to-face interviews. After controlling for sociodemographic and economic factors, health status, and insurance coverage, Mexican Americans who were less acculturated had significantly lower probabilities of an outpatient medical visit for physical health problems and of a visit to a mental health specialist or human service provider for emotional problems. The less acculturated with good perceived general health were especially unlikely to receive outpatient medical care. Having Medicaid coverage was associated with a larger increase in the probability of an inpatient medical admission for the more acculturated than for the less acculturated. Other individual characteristics had generally similar effects on use of medical and mental health services for both the more and the less acculturated Mexican Americans.