To understand contextual associations between medical care providers-pediatricians, family medical practitioners, and alternative medicine practitioners-and personal belief exemptions (PBEs) from mandated school entry vaccinations.Data on kindergarten PBEs from the California Department of Public Health were analyzed for 2010, 2011, and 2012, with each school sorted into Primary Care Service Areas (PCSAs). Provider data from federal sources and state records of alternative medicine providers, alongside controls for school factors, were used to estimate panel models.Each 10% increase in the relative proportion of pediatricians in a given PCSA was associated with a statistically significant 11% decrease in PBE prevalence. The same increase in the proportion of family medical practitioners was associated with a 3.5% relative increase. Access to alternative medicine practitioners was also associated with a significantly higher PBE prevalence.Medical provider contexts are associated with PBEs, reflecting a combination of contextual effects and self-selection of families into schools and PCSAs that share their preferences. The geographic distribution of child primary care services may be a key factor in a school's health risk associated with lack of immunization or underimmunization.