Hybrid simulations with electron inertia, along with analytic scaling arguments, are presented which demonstrate that magnetic reconnection remains Alfv¿nic in a collisionless system even as the macroscopic scale length of the system becomes very large. This fast reconnection is facilitated by the whistler physics present near the x-line. The reconnection rate is found to be a universal constant corresponding to an inflow velocity towards the x-line of around 0.1 cA. ¿ 1999 American Geophysical Union