Clinical conversations between health professionals and parents can be frustrating for both parties when the topic is childhood immunization. Parents bring to the table personal models of decision making and experiences of risk that may differ from those of their health care providers. They may also feel confused by an explosion of information available through the popular media, Internet Web sites, public health agencies, and medical professional organizations. In this article, it is argued that parents' trust toward health care providers is a key to addressing parent worries about vaccines. Suggestions for understanding the bases of parent concerns and supporting parents' decision making are provided.