Using a fuzzy-trace theory approach, the purpose of this study was to examine whether demographic variables such as age, race/ethnicity, or education are related to COVID-19 prevention behaviors and whether gist principles of responsibility mediate these relationships. A sample of 467 college students and 1459 people from the community took a survey about their COVID-19 prevention behaviors such as wanting to get vaccinated and social distancing. Across both samples, people were more likely to engage in COVID-19 risk-reduction behaviors who were older, identified as female, identified as Asian or Pacific Islander, had higher levels of education, identified as Democrats, had a liberal ideology, or were students. Agreeing with gist principles of responsibility was positively associated with COVID-19 prevention behaviors and mediated most of the relationships between the demographic variables and COVID-19 prevention behaviors. Demographics and gist principles of responsibility are important factors for researchers to consider when creating interventions to promote engagement in COVID-19 prevention behaviors. However, these factors cannot be taken at face value and internal differences in culture and cognition need to be taken into account to explain and improve health behavior.