The chapter aims to provide a classification of different philosophical theories of well-being. A very common issue of contestation is whether well-being is subjective or objective. However, ontological and evaluative perspectives in this regard need to be disentangled. The ontological perspective is concerned with the problem whether well-being is a mode of consciousness or of existence. The evaluative perspective focuses on the criteria of well-being. There are then altogether four different accounts: (i) experience theories (ontological subjectivism), (ii) state-of-being theories (ontological objectivism), (iii) desire-fulfillment theories (evaluative subjectivism), and (iv) essence theories (evaluative objectivism). This classification is applied to a particular philosophical and social dispute, namely, whether and, if so, in what way disability undermines the quality of life of persons with disability.