This is an introduction to the special issue "Vaccine Hesitancy and Refusal." This special issue of Health Psychology examines various aspects of vaccine hesitancy using a health psychology lens. The timing of this issue, following a call for papers issued in the summer of 2021, in the midst of the COVID-19 pandemic, is reflected in the focus on COVID-19 vaccine hesitancy in the papers included here. This is important, as the field of vaccine hesitancy research has expanded greatly in response to the COVID-19 pandemic. As of March 2, 2023, a search of PubMed for "vaccine hesitancy" yielded 5,635 papers, dating back to 1968. A similar search for "COVID vaccine hesitancy" yielded 3,851 papers, starting in 2020. This highlights the need for new and novel theory-based interventions that can be broadly applicable to hesitancy to other routine vaccinations. (PsycInfo Database Record (c) 2023 APA, all rights reserved).