In order to evaluate the applicability of power politics theories of war and international stability to interactions among nonstate actors, I test hypotheses from power transition theory and from neorealist arguments about systemic polarity against the behavior of 20 state and nonstate actors in nineteenth-century South America. I find considerable support for two of the three hypotheses tested and conclude that existing IR theory has more explanatory power within the empirical domain of nonstate relations than critics of such theory claim.