The growing influence of managed care in mental health services has raised important questions about access to services. This article introduces and demonstrates a global measure of access that is based on the relationship between service utilization and the need for services. This measure has become practical because of recent advances in measurement technology that provide more valid and reliable estimates of the prevalence of mental illness in general populations and of the number of people who receive mental health services across service sectors. The methodology is used to produce a report card type profile of access to inpatient mental health services (in state, general, private and veterans hospitals) by residents of one state. This global measure can provide a powerful and efficient tool for monitoring and comparing the impact of managed care plans on access to mental health services.