One of the many established predictors of conspiracy beliefs is reflective thinking, but no meta-analysis so far has examined this relationship. In the current meta-analysis of published and unpublished correlational data (145 samples, 181 effect sizes), we found a significant negative association between reflective thinking and conspiracy beliefs with a medium-level effect size (r = –.189) . Similar levels of correlations were found across different types of measures (self-report vs. performance-based) and conspiracy beliefs (generic vs. specific). Further, no evidence suggested publication bias in this body of work. Suggestions for future research are discussed.