This article begins with an assessment of the similarities and differences between terrorists and criminals, including profiles, methods, systems of organization and motives. Notably, the article identifies seven categories of crimes committed by terrorists: 1) Inherent/violent, 2) Preparation/facilitation, 3) Funding, 4) Specialized terrorism offenses, 5) Vigilantism/public relations, 6) Miscellaneous/Spontaneous/Unrelated Offences, and 7) Previous criminal records. Next, the crime-terror nexus is discussed and four types of relationships between terrorists and criminals are identified: 1) Interaction, 2) Appropriation, 3) Assimilation, and 4) Transformation. The article concludes with a discussion of the concept of convergence between terrorism and organized crime, and implications for counter-terrorism and law-enforcement.