This article examines the various ways in which the self is (or is not) involved in conscious and unconscious mental life. The self may be construed as a cognitive structure representing a person's knowledge of him or herself. This knowledge structure may take the form of a concept, image, or a node in an associative network of memories. Conscious states are not just represented in working memory (e.g., the "global workspace"), but must be linked to a mental representation of the self (as agent or patient, stimulus or experiencer), also represented in working memory. In unconscious mental life, as exemplified by automatic processing or explicit-implicit dissociations, this aspect of self-reference is missing, giving rise to effects that occur outside of phenomenal awareness. At the biophysical level of analysis, the self may be represented by a single "grandmother" neuron, a sparse network of neurons, or it may be widely distributed across the cortex. Viewed phylogenetically, ontogenetically, or culturally, the development of consciousness may be intimately tied to the development of the sense of self.