This article analyses the nexus of public attitudes toward military missions abroad, specific beliefs about the respective missions, and political predispositions. While some studies have argued that specific beliefs such as success expectations are the most important explanatory factors of attitudes, others have stressed the role of party-related predispositions in shaping both beliefs and attitudes. Using the case of German citizens’ attitudes toward the German participation in the International Security Assistance Force mission in Afghanistan, we argue that scope conditions determine the relative merit of these perspectives. With data from a representative survey conducted in 2010 we show that in this late stage of the military mission, success expectations had a substantial effect on German citizens’ mission support that was not merely mediating the influence of predispositions. At the same time, foreign policy predispositions also had a substantial impact on mission support, while party identifications had only minor effects. We discuss the more general implications of these results for statements on the relative importance of predispositions and specific beliefs as explanatory factors in public opinion formation on the use of military force.