This paper puts forward "The Conceptual Referent Theory of Happiness" (CRT), which states that a person's conceptual referent for a happy life plays a role in the judgment of her life and in the appraisal of her happiness. A typology of eight conceptual referents for happiness is made on the basis of a review of philosophical essays on happiness. The theory contributes to the understanding of happiness by focusing on a cognitive factor involved in the judgment process: A person's notion of what a happy life is, of what she understands for being well. Thus, CRT complements previous research by studying what a person thinks, rather than what she feels, at the time of appraising her life. CRT also stresses the importance of heterogeneity; this is: the conceptual referent is not the same for every person; people have different conceptions of what a happy life is. Hence, the investigation studies the issue of superiority in the conceptual referent for happiness. It shows that no conceptual referent can be considered as superior in the sense of being associated to greater happiness. However, there are a few conceptual referents that are clearly inferior. The investigation also studies the influence of socioeconomic and demographic variables in the conceptual referent a person holds. It shows that the probability of embracing a particular conceptual referent for happiness is contingent on a person's socioeconomic and demographic situation. The empirical investigation is based on data from a large survey applied in Mexico.