This chapter analyses the relationships between neighbourhood peer groups and members of criminal networks in post-Soviet urban spaces. It addresses the illicit territorial governance by street youth groups and criminal communities by looking at the relationships between the members of youth street organisations and criminal groups in Moscow and in Tbilisi. The chapter discusses the origins and the social and cultural influence of the Soviet and post-Soviet criminal communities of thieves-in-law. It also analyses the patron-client relationships between the thieves and youth groups, and the role of professional criminals in the local social regulation. The chapter also discusses the case studies conducted in Moscow and Tbilisi. It concludes with the interplay between the illicit systems of regulation and local social and cultural traditions, and of the changing relationship between formal state regulation and the alternative street systems.