Parents' trust in information sources on vaccines influences their decision to vaccinate their children. This study explores how trust in information sources can promote or reduce vaccine hesitancy among parents. We conducted a systematic review and qualitative meta-synthesis of 29 vaccine hesitancy studies that focused on information and trust. We found that parents were particularly distrustful of (1) pharmaceutical companies, (2) physicians, (3) the government, and (4) academic research. Distrust partly stemmed from a belief that pharmaceutical companies unduly influenced physicians, the government, and academic research to maximize financial profit at the expense of population health. A non-judgmental, nonpartisan approach-whether with health care providers or family and friends-increased parents' trust in the information source. Strategies that address parental concerns regarding scientific research and improve communication between parents and providers may increase adherence to vaccination schedules.