Health care providers exert a significant influence on parental pediatric vaccination decisions. We conducted hour-long interviews with traditional and alternative health care providers in which we explored a range of associations between vaccination perceptions and practice. A key finding was that the Health Belief Model constructs of perceived susceptibility to and severity of either an illness or an adverse vaccine event partially explained health care provider (HCP) beliefs about the risks or benefits of vaccination, especially among alternative care providers. Low or high perceived susceptibility to a vaccine-preventable disease (VPD) or of the severity of a given VPD affects whether an HCP will promote or oppose pediatric vaccination recommendations. Beyond these perceptions, health and vaccination beliefs are affected by the contextual factors of personal experience, group norms, immunology beliefs, and beliefs about industry and government. Building powerful affective heuristics might be critical to balancing the forces that defeat good public health practices.