Objective To examine the effects of distance to dentists and dentist supply on dental services use among children with Medicaid coverage in Iowa. Data Source Iowa Medicaid claims for enrolled children between 2000 and 2009. Study Design The study sample included 41,554 children (providing 158,942 child‐year observations) who were born in Iowa between 2000 and 2006 and enrolled from birth in the Iowa Medicaid program. Children were followed through 2009. We used logistic regression to simultaneously examine the effects of distance (miles to nearest dentist) and county‐level dentist supply on a broad range of dental services controlling for key confounders. Additional models only used within‐child variation over time to remove unobservable time‐invariant confounders. Principal Findings Distance was related to lower utilization of comprehensive dental exams (2 percent lower odds per 1 mile increase in distance), an effect that also held in models using within‐child variation only. Dentist supply was positively related to comprehensive exams and other preventive services and negatively related to major dental treatments; however, these associations became smaller and insignificant when examining within‐child changes except for other preventive services. Conclusions Longer distance to dentists is a barrier for use of comprehensive dental exams, conditional on dentist supply.