This paper reviews literature on the case structure of subjective well-being and examines the support for a number of proposed well-being dimensions. It is considered that a distinction between cognitive and affective dimensions is conceptually useful, but poorly researched. Clear support, however, is available for a distinction between positive and negative affective dimensions, as well as for a general second-order dimension of subjective well-being. Proposals for a distinction between inner and outer dimensions of well-being are considered promising but speculative at present. Although the intensity and frequency of affective experience are clearly distinct, it is considered that affect intensity should not be regarded as a dimension of well-being. Three issues related to the dimensionality of well-being, The time focus of assessment, attempts at cross-classification of dimensions, and research on the stability of well-being structure, are also discussed. Although considerable research into subjective well-being exists, the structure of well-being is not yet well established or researched.