Childless adults in the Medicaid expansion population have complex social and behavioral needs. This study compared the cross-sector involvement of Medicaid expansion enrollees who were high health care utilizers to that of other expansion enrollees in Hennepin County, Minnesota. We examined forty-six months of annualized utilization and cost data for expansion-eligible residents with at least twelve months of enrollment (N = 70,134) across health care, housing, criminal justice, and human service sectors. High health care utilizers, approximately 7 percent of our sample, were disproportionately American Indian, younger, and significantly more likely than other expansion enrollees to have mental health (88.1 percent versus 48.0 percent) or substance use diagnoses (79.2 percent versus 29.6 percent). Total cross-sector public spending was nearly four times higher for high health care users ($25,337 versus $6,786), and their non-health care expenses were 2.4 times higher ($7,476 versus $3,108). High levels of cross-sector service use suggest that there are opportunities for collaboration that may result in cost savings across sectors.