We present a comprehensive taxonomy of outcomes for childhood vaccination communication interventions. Adding to our earlier map of trial outcomes, we aimed to (1) identify relevant outcomes not measured in trials, (2) identify outcomes from stakeholder focus groups, and (3) organize outcomes into a taxonomy.We identified additional outcomes from nonvaccination health communication literature and through parent and health care professional focus groups. We organized outcomes into the taxonomy through iterative discussion and informed by organizational principles established by leaders in core outcome research.The taxonomy includes three overarching core areas, divided into eight domains and then into outcomes. Core area one is psychosocial impact, including the domains "knowledge or understanding," "attitudes or beliefs," and "decision-making." Core area two is health impact, covering "vaccination status and behaviors" and "health status and well-being." Core area three is community, social, or health system impact, containing "intervention design and implementation," "community participation," and "resource use."To our knowledge, this taxonomy is the first attempt to conceptualize the range of potential outcomes for vaccination communication. It can be used by researchers selecting outcomes for complex communication interventions. We will also present the taxonomy to stakeholders to establish core outcome domains.