This article presents a new integrative analytical framework for studying and understanding the multitude of processes that make intrastate armed conflicts become internationalized in a broad conceptual sense. The authors attempt to shift the debate beyond the dichotomy of international vs. transnational dimensions of civil wars and argue that numerous aspects of this process can essentially be interpreted as part of a complex phenomenon which is to be studied through the lens of a comprehensive analytical system. To this end, the authors conceptually distinguish between the three dimensions of conflict internationalization with the horizontal escalation leading to spatial spread, the vertical escalation expanding the conflict structure and the systemic escalation transforming its relevance within a larger international system. More importantly, the paper elaborates on how various processes that occur along different dimensions - and that have been grasped by a plethora of both theoretical and empirical contributions in the fields of IR and conflict studies - connect to one another creating both reinforcing and counterbalancing systemic loops that determine the international, transnational and cross-border scope of an internal conflict. The resulting three-dimensional analytical framework can be applied at both region-specific and conflict-specific levels. To demonstrate the former, the authors provide a sample application of the framework to the realm of armed conflict internationalization in Southeast Asia illustrating how varied instances of diffusion, intervention, externalization and proxy-structuring have driven one another creating patterns specific for this region.