his article examines the theoretical and practical aspects of interagency cooperation between internal affairs agencies and other law enforcement agencies in the area of constitutional law and order. It analyzes conceptual frameworks, demonstrates the relationship between the categories of “interaction”, “cooperation” and “coordination” and provides a definition of cooperation as it applies to law enforcement. The characteristics of interagency cooperation among law enforcement agencies are examined and systematized. The outlines of an optimal model of interagency cooperation are proposed, highlighting its institutional, procedural, organizational-managerial and functional-tactical forms. The need to develop and improve the effectiveness of the existing system of interaction among law enforcement officers is demonstrated and promising areas for improving interagency cooperation are identified.