In three studies, I found evidence that people living in less socially inclusive countries (operationalized as having weaker rule of law, and lack of equality and press freedom) have a greater tendency for conspiracy ideation. In Study 1 (21 countries, N = 22,238), participants in less inclusive countries were more likely to believe in conspiracies, even after adjusting for country-level differences in educational performance. Study 2 (24 countries, N = 4,743) and Study 3 (23 countries, N = 5,726) replicated this result by using individual-level education status and scientific literacy as covariates, respectively. The associations between inclusiveness and conspiracy beliefs was stronger for people with higher levels of educational attainment and scientific literacy. I argue that this is because real conspiracies are more likely to actually happen in less inclusive contexts; thus, it is more rational to have increased levels of suspicion of secret and hostile alliances in such countries.