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structured, and the reader is well guided through the chapters. The author does a very good job of spelling out the contribution to the existing literature. Moreover, Mello makes a case for the superiority of fsQCA over both quantitative approaches and case studies. He stakes out his claims well, but his arguments are not always convincing. For example, it does not become clear why fsQCA should be superior to a quantitative test of the hypotheses apart from the fact that the data are missing with regard to the latter. A clear focus on and argument for fsQCA’s ability to provide a different causal pathway might have been more convincing. In addition, Mello’s desire to make a methodological contribution besides an empirical one leads to an overemphasis on methods. There is no explanation as to why it is necessary to explain the coding procedure in such great detail for each case study, especially if the procedure is almost identical over the case studies. Here, it would have been more efficient to either explain the coding procedure for all cases in the methods chapter or move these parts to the appendix. A substantial interpretation and contextualization of Mello’s findings would also have been useful. The most important and robust finding that constitutional constraints matter for war participation is not sufficiently discussed in view of its political relevance. Thus, the most compelling message almost gets lost. Additionally, the relevance of other cogent factors, such as military power, is hard to generalize across the cases, especially as the empirical chapters do not always discuss the same factors. Overall, Mello’s contribution is highly elucidating and provides an important piece of the puzzle to the democratic peace literature, even if it is overtly wedded to and ultimately constrained by its method.