Abstract: A vehicle anti-lock braking system having a master cylinder operated upon operation of a brake operating member, a wheel cylinder activated by a pressure produced by the master cylinder, and an anti-lock control device which includes a slip ratio detector for detecting a slip ratio of a drive wheel of the vehicle, and a pressure regulating device for controlling a pressure in the wheel cylinder, so as to maintain the slip ratio in an optimum range. The system also has a traction control device including a traction control power source, and a communication switching device for selective communication of the pressure regulating device with the traction control power source or the master cylinder.