The paper focuses on the analysis of conspiracy beliefs and conspiracy theories by taking into consideration some of the major contributions about the topic presently provided by several disciplines. A definition is given that helps illustrate the most prominent features of these beliefs, namely monological bias, logical and conceptual fallacies, dispositional influence and pseudorationality. Other important psychological preconditions are also provided (such as, among others, credulity, hypersensitive agency detection devices and proneness to self-deception), but, as the paper argues, they are (...) features shared to a greater or lesser extent with other belief systems, like radical political ideologies and religious fundamentalisms. As a result, it is suggested that a more proper understanding of the phenomenon is attainable by approaches combining psychological data with the analysis of groups and sociopolitical dynamics. Exceptional contingencies and shifts in power distribution among group/social actors seem to be the most influential factors that explain formation, spread and salience of this kind of beliefs. (shrink)