This chapter aims to address conspiracy theorising across cultural contexts. It provides the only cross-nationally-representative data focusing on conspiracy theories currently available. The chapter shows how cultural context conditions conspiracy theorising and as a consequence may frustrate attempts to study conspiracy theories cross-culturally. Conspiracy beliefs are individuals’ acceptance of specific conspiracy theories as likely true. Many researchers skip the step of systematically measuring conspiracy beliefs or thinking, and instead rely on impressions. Conspiracy beliefs are partially dependent on demographic characteristics and group memberships because they cast one’s own group as a victim of other groups. If conspiracy thinking is related to feelings of marginalisation, anomia and helplessness, then higher income levels should negatively predict belief in conspiracy theories. Studying conspiracy theories is important for understanding contemporary political life. Much of the theorising of who counts as a conspiracy theorist has taken place in the USA and other English-speaking areas.