The present paper contains legal and practical aspects of Police activities in order to counteract juvenile demoralization and delinquency. It demonstrates the degree and structure as well as the causes of juvenile delinquency in Poland, which reveal a worrying tendency of increasing aggressive behaviour among adolescents. The paper attempts to disclose the underlying reasons of aforesaid increase taking as a basis resolved cases of delinquent juvenile behaviour. We specified the legal regulations as indicated by the legislative organ as well as by internal police directions. We focused on practical issues within the scope of police operations and activities in this domain. The conclusions refer to the practical aspects of the execution of police tasks focused on crime prevention and the dealing with aforesaid phenomena, taking under special consideration the necessity of concerted professional actions and cooperation with other authorities to attain a common goal.