A common method employed within various national jurisdictions, utilized to counter organized crime, extremism and similarly felonious activities has been to legislate criminal prohibitions against actively participating in the very organizations within which these activities occur. Such legislation, however, has turned out to be a frequent subject of discussion for criminal law theorists. The legitimacy of criminalizing participation in and other types of involvement with criminal (and similar) organizations may be doubted, in light of various, often recited principles in criminal law theory and legal philosophy. This thesis examines these doubts and evaluates whether this type of criminalization fully meets the standards set by the aforementioned principles.