Conspiracy mentality is a general tendency to attribute significant events to the actions of malevolent actors, without referencing to a specific event. In two independent representative surveys of adult Serbian citizens (N1 = 1194; N2 = 1258) we validated Serbian version of the conspiracy mentality questionnaire (CMQ), a reasonably content-free tool designed to capture global conspiratorial beliefs. We successfully validated the adapted CMQ and replicated findings on two national representative samples. In both studies the results demonstrated: good psychometric properties of the CMQ and its predictive capacity for endorsing the international Conspiracy Theories (CTs) (Study 1) and the locally specific CTs (Study 2) over and above the measures of perceptions of political climate (trust in institutions, corruption perception, feeling of insecurity – Study 1), and generalized political attitudes (right-wing authoritarianism, social dominance orientation, political cynicism – Study 2). The study presents a unique adaptation and implementation of the CMQ in the non-English speaking country with very active and widespread conspiracy beliefs and a long history of conflicts.