The 1980s have witnessed a resurgence of interest in the self. Not only have new models proliferated, but a number of investigators have sought theoretical guidance from historical scholars of the past. In our own work, we have drawn upon the insights of William James (1892) and Charles Horton Cooley (1902). In this chapter we build upon the legacy of James and Cooley, particularly with regard to an understanding of the determinants of self-regard or self-worth. We adopt a developmental perspective in that we focus on how the child's sense of overall worth as a person is constructed. A major goal of our research has been to operationalize the formulations of both James and Cooley, in order to provide a test of their appropriateness in accounting for individual differences in self-worth. We have also sought to examine the issue of whether self-worth is merely an epiphenomenal construct or whether it plays a role in mediating one's affect and one's motivational level. Since a detailed description of this work has appeared elsewhere (see Harter, 1986b, 1987), this chapter merely summarizes the model and supporting evidence.