Collusion to commit a crime is considered one of the important institutions of contemporary criminal law, which has always been the subject of serious theoretical debates and differences of opinion due to its location on the border between criminal thought and the beginning of the execution of the crime. The importance of this institution lies in the fact that in some cases, the mere voluntary agreement between two or more persons to commit a crime, even before the actual conduct, can be the basis for criminal liability. In the Iranian legal system, the criminalization of collusion has been given the attention of the legislator sporadically, mainly in the field of crimes against the internal and external security of the country (the subject of Article 610 of the Islamic Penal Code). In this framework, the realization of criminal liability often requires the existence of a criminal agreement along with preliminary measures in order to commit the crime, even if the final result is ruled out for reasons beyond the will of the perpetrators. In contrast, French criminal law, with a more systematic approach, has criminalized criminal agreement, especially in organized crimes and major crimes against public security and order, as one of the preventive tools of criminal law. The present study, using a descriptive-analytical method and a comparative approach, examines the material and moral elements of collusion, as well as the theoretical and criminal policy foundations of its criminalization in the two legal systems of Iran and France.