ABSTRACT: This article develops the idea of "dirty money states" by defining and exploring the problem of illicit state financing in Southeast Asia. Most diagnoses of Southeast Asia's flourishing illicit economies focus on the prevalence of corruption and the "decay" of the state, but the authors of this essay develop a more nuanced explanation by exploring how states cultivate and sustain themselves through illicit extraction. Drawing from emerging literature on states and criminality, as well as fiscal sociology, they develop a novel theoretical framing for the six country case studies that comprise this thematic issue. Each study - on Indonesia, Cambodia, Vietnam, Myanmar, East Timor, and the Philippines - examines empirically how illicit state financing works. Whether revenues derive from gold, timber, opium, aid agencies, or business interests, the authors identify consistent patterns in the nature and behavior of the state vis-à-vis illegally generated funds. These patterns encompass territorial dynamics and practices; the everyday social worlds of state actors and their entrepreneurial allies; and the paradoxical interplay between formal and informal realms. Ultimately the authors argue that illicit monies are fundamental to contemporary state building in the region, extending even to the delivery of public goods and services. These findings are potentially uncomfortable for scholars, governments and development practitioners, particularly because they challenge conventional ideas about how the strength and/or weakness of states might be understood in Southeast Asia. But they demand attention, since they are the product of an ambitious and unconventional research endeavor.