Conspiracy theories have been highly relevant for several decades, as various publications show. However, what has been lacking until now is a comprehensive manual documenting this controversial field of research. The present handbook, which also serves as a reference work on antisemitism, aims to introduce a sensitive yet very complex topic. It attempts to summarize the widely scattered and extensive literature and to clarify the various forms and typologies of conspiracy thinking. In this handbook, conspiracy theories are viewed as part of the still prevalent global antimasonry and antisemitism, which have hardly lost weight in terms of aggressiveness and exaggerated polemics. Antimasonry is an ideology that primarily targets Freemasonry for political and religious reasons.