In recent years, terrorist groups intensified their cooperation with criminal entities or their independent engagement in criminal activities. But why and how, exactly, is cooperation with criminal actors beneficial for terrorist groups? And under which political and economic conditions are criminal and terrorist entities more inclined to cooperate or coordinate their operations? Despite the growing interest of academics and practitioners in the nexus of crime and terrorism, we are still unable to answer such questions authoritatively, and, in general, we are lacking in our understanding of the operational characteristics of these connections. The current study utilizes a global dataset of cases of cooperation between terrorist and criminal groups in order to try and answer some of these questions. Our findings indicate that both organizational and environmental factors can predict the likelihood of collaboration. More specifically, group structure, lifespan, ethnic/religious compatibility, geographical proximity, and the existence of criminal infrastructure are all associated with the tendency of criminal and terrorist groups to cooperate. Lastly, corporate and established terrorist groups are more inclined to engage in multiple low-end cooperation rather than high end.