Alliances and arms races have received considerable attention in the causes-of-war literature. While a large amount of empirical research has pursued these topics separately, multivariate conditional combinations of these processes have been relatively scarce to date. An argument for doing so is provided by Vasquez's steps-to-war theory which organizes international relations into an interactive complex of factors, including territorial disputes, interstate rivalry, recurrent crises, alliances, military buildups, and war onset. A model linking indicators of these processes is developed and tested for the 1919–95 era. Substantial empirical support for their interactions emerges. Territorial disputes in the context of rivalry and recurrent crises, aggravated by military buildups and asymmetrical external alliance situations, combine to make escalations to war more probable. Hopefully, an improved understanding of interstate escalatory dynamics can serve as a foundation and stimulus for more interactive attempts to unravel the puzzle of war causation.