Three decades of research in magnetospheric substorms has not led to a general consensus view of the substorm process. Several substorm models, mostly phenomenological, are presently under consideration. These competing models, each being justifiable on the basis of certain features of a substorm, have major differences as well as similarities among them. A synthesis substorm model is desirable, as first suggested by Siscoe (1986). In this paper we construct a coherent description of substorm development by extracting some important components from these existing models. The scenario of the synthesis model includes the ionospheric influence on substorm expansion onset, current disruptions leading to convection surges and tailward propagating rarefaction waves, wave-induced precipitation, local time expansion of the disturbance region via velocity-shear-related instabilities, plasma sheet heating by resonant absorption of hydromagnetic waves, and the formation of magnetic reconnection domains. This synthesis represents one possible way to integrate the different existing models coherently. ¿American Geophysical Union 1990