Using the grounded theory method, a substantive theory of postpartum depression was developed. Data were obtained through participant observation in a postpartum depression support group over an 18-month period. In addition, 12 in-depth taped interviews were conducted with mothers who had attended the support group. Analysis of the data by the constant comparative method revealed loss of control as the basic social psychological problem. Women suffering from postpartum depression attempted to cope with the problem of loss of control through the four-stage process of teetering on the edge. The stages that emerged from the data included (a) encountering terror, (b) dying of self, (c) struggling to survive, and (d) regaining control.