To assess what characteristics of children and their communities are associated with lower dental service use rates, to support development of strategies to target subgroups of children with lower utilization. The Medicaid Analytic Extract (MAX) 5-percent sample file, known as Mini- MAX 2008. Multivariate logistic regression was used to assess the association between enrollee and county characteristics and dental preventive and treatment service utilization. There is substantial variation in service use by age. Relative to a 9-year-old, a 2-year-old is 28 percentage points less likely, and a 15-year-old is 15 percentage points less likely, to receive a preventive dental service. Children enrolled in Medicaid for only part of the year were significantly less likely to receive a preventive or a treatment service relative to children covered by Medicaid for the full year. For preventive care, children enrolled for nine months were 15 percentage points less likely to have a service. Those enrolled for six months were 30 points less likely; those enrolled for three months were 41 points less likely. Children eligible for Medicaid based on disability were 9 and 6 percentage points less likely to receive a preventive or treatment service, respectively, than their counterparts who were eligible based on income alone. This study identifies some subgroups of children who are particularly underserved and for whom states may need to devote more attention.