This paper compares the capability approach (CA) and libertarian paternalism (LP) to see whether they are compatible. The comparison focuses on rationality, wellbeing, and freedom. The main theoretical framework is Sen’s ‘reason to value’ (RtV). The relevance of this to CA, and LP is analysed, and whether the primacy that CA and LP both accord to reason leads to paternalism is examined. Although the principal focus is on Sen’s, Sunstein’s and Thaler’s original ideas, their key concepts are analysed in the context of the contemporary critical literature on the topic. This critical analysis not only makes it possible to assess whether CA and LP are compatible, but also to see how they perceive rationality, wellbeing, and freedom. The critical analysis further differentiates the various interpretations of RtV in the literature and explains how CA and LP function.