Criminal syndicates have been around for millennia. While some were founded to undertake cross-border activities, others have expanded internationally, evolving into sophisticated organizations that mimic multinational enterprises. The growing prevalence of criminal multinational enterprises (CMNEs) provides an opportunity to revisit international business theory, particularly internalization theory. We start by defining the CMNE, explaining its rise and interface with legitimate multinationals, and establishing similarities and differences with legitimate multinational enterprises. Then, we use the CMNE to “stress-test” the internalization theory of the multinational enterprise, set its boundaries, and offer theoretical development by way of extension, qualification, and refinement.