P hilosophers and psychologists have long been interested in understandingthe nature of self. As the various chapters in this book demonstrate, psychol-ogists have learned a great deal, although many questions remain. Chief among these is how activity in the brain gives rise to the unitary and coherent sense of self that exists across time and place. Recently, researchers have started to use the methods of neuroscience in their efforts to explore questions about the self. The advent of imaging techniques over the past two decades has provided researchers with the capacity to study the working brain in action, thus providing a new window for examining previously intractable mental states, including the phenomenological experience of self (Macrae, Heatherton, & Kelley, 2004). In this chapter, we describe neuroimaging work on three primary aspects of self: the cognitive self (i.e., self-knowledge), the affective self (i.e., self-esteem), and the executive self (i.e., self-regulation). We do not intend this to be an exhaustive review of the neurobiology of self. Rather, our goal is to demonstrate how studying the brain can inform psychological research on various aspects of the self.