There are various approaches, both simple and complex, to systemic conflict. The simpler ones include balance of power, polarity, concentration, polarization, and democratization. More complex systemic approaches to conflict range from power transition and relative power cycle to leadership long cycle and world-systems. Some of these programs continue to generate scholarly interest and produce new findings, while others have been beset with little activity. Yet, none of these research programs have captured enough scholarly attention to be fully “mainstreamed.” That is, they have not been co-opted as central interpretations of international politics. The theoretical literature on simpler approaches to systemic conflict persists today but was more common prior to the mid-1970s. Since systemic analyses were not well developed in the first two or three decades after World War II, scholars grappled with what systemic analyses meant. One question is whether we should differentiate between a global system and its multiple regional subsystems. Complex systemic research programs have declined in analytical popularity after peaking in the 1980s, in large part because perceptions of the world situation changed in the 1990s. Whether “traditional” system dynamics will regain its lost status in light of the globalization processes perceived to be at work remains unclear, but there is cause for optimism about the future contributions of systemic theory as research programs in this area have expanded to include new topics and issues, along with new theoretical developments in other areas that will be pertinent to systemic perspectives.