Since the terrorist attacks on the United States in September 2001, the fight against international terrorism has become a priority for international organizations and states. These attacks have highlighted the existence of connections between international terrorism and organized crime with the involvement in drug trafficking and weapons, as well as illicit financial activities. The responses by states to terrorism and organized crime, two phenomena that create considerable social panic, have been selective and random interventions in the absence of a common strategy. As far as international terrorism, a series of rules were introduced focusing on certain types of terrorist acts. On the universal level, the United Nations, as well as other institutions adopted some conventions with some being ratified dealing with specific aspects of the phenomena. A coherent legal framework was established through the Palermo Convention which has not yet come into force. To tackle the problem of the need to punish the crime of association, it would be appropriate to start at the state level. Dealing with the connection of terrorism and organized crime at the state level adequately delimits the respective scope of application of the provisions for crimes committed by associations. However, states may have great difficulties in fighting the connections between terrorist groups and ordinary criminal organizations, since the cooperation mechanism currently in force does not allow for effective collaboration. There are also problems of the state-of-the-art of cooperation at the global level, which does not appear very satisfactory and could be exploited by criminal groups. The desire is to prevent terrorism from becoming an obstacle to international cooperation.