Current research on coalition formation is plagued by two serious problems. First, we cannot predict more than about one-third of the Western European governments, and, second, we do not have a good understanding of the causal mechanisms that explain the effects found in large-n coalition studies. This article illustrates that by combining statistical and case study analyses we can solve these problems. Since statistical analyses are well equipped for measuring and isolating effects, we argue that a coalition study should start with such an analysis. Predictions made in this analysis are then used to select cases. In order to study the mechanisms underlying effects found in large-n coalition studies, we argue for selecting cases that are predicted, and then applying the method of process verification. In order to find new explanatory variables, we argue for selecting cases that are deviant, and then applying the method of process induction. Substantive results of our analysis for coalition theory point to the importance of party strategies based on parties' past experiences, which aim at curtailing present and future costs of competing and governing with other parties.