This study addresses the political and economic basis of milícias in the city of Rio de Janeiro and the effects of government regulation of legal and illegal markets on their expansion. The period under study was 2007-2020 -of remarkable expansion of milícias -and the information analyzed were accessed from three different databases: 1) the Map of Armed Groups in Rio de Janeiro; 2) Data on police raids between 2007 and 2019 from the GENI/UFF database; 3) data from the City of Rio de Janeiro Secretariat of Urbanism (SMU) database in the period between 2009-2019.