The article is devoted to the study of criminal groups of convicts in places of deprivation of liberty as one of the most dangerous factors destabilizing the functioning of the penal enforcement system. The paper examines historical and contemporary forms of informal organization among convicts, the specific features of criminal stratification, the influence of criminal subculture, as well as the processes of radicalization among certain categories of inmates. Particular attention is paid to the correlation between the concepts of “criminal group,” “organized group,” and “criminal community” in relation to crime within correctional institutions. Based on the analysis of academic literature, criminal legislation, and empirical data, the author formulates proposals aimed at improving criminal law mechanisms for counteracting organized crime in places of deprivation of liberty.