Qualitative Comparative Analysis (QCA) is a set-theoretic comparative method that treats cases as configurations of conditions, aiming to identify those conditions and/or combinations that are necessary and/or sufficient for an outcome. This chapter opens with a review of how the method has been applied empirically in the fields of Foreign Policy Analysis (FPA) and International Relations (IR). This is followed by an introduction to the method’s assumptions and key terminology. The third part provides an illustration of how QCA works in practice, drawing on a published study. The chapter closes with a discussion of the method’s strengths and limitations, together with recommendations on how to avoid frequently encountered mistakes.