The transition in the magnetic reconnection rate from the resistive magnetohydrodynamic (MHD) regime where the Alfv¿n wave controls reconnection to a regime in which the ions become unmagnetized and the whistler wave mediates reconnection is explored with 2--D hybrid simulations. In the whistler regime the electrons carry the currents while the ions provide a neutralizing background. A simple physical picture is presented illustrating the role of the whistler in driving reconnection and the rate of whistler mediated reconnection is calculated analytically. The development of an out-of-plane component of the magnetic field is an observable signagure of whistler driven reconnection. ¿ American Geophysical Union 1994