A hypothetical mechanism is described whereby the QBO of zonal winds in the lower tropical stratosphere alters the distribution of intense deep convective activity throughout the tropical West Pacific. In conjunction with the annual cycle and the buildup of heat in the West Pacific warm pool, these QBO-linked variations of deep convection cause variations in the Central Pacific trade winds and Walker circulation which in turn govern the occurrence of ENSO events in the tropical Pacific. Although some details of the hypothetical mechanism are tentative, empirical results present a compelling argument for the stratospheric QBO to at least partly regulate ENSO variability. ¿American Geophysical Union 1992