This study explores the extent and consistency of heavy use of acute psychiatric inpatient services among Medicaid recipients across five years and four sites. Approximately 35% of inpatient service users account for approximately 75% of the dollars spent on inpatient services across place and time. Heavy users are distinct from non-heavy users in being comprised of more children and adolescents, in being disproportionately white, and in having more severe disabilities. The study findings are discussed in the context of the planning of appropriate services for this patient subgroup.