Abstract: A vehicle traction controller includes engine control and brake control routines to improve vehicle traction. The engine control routine reduces average slip of driven wheels of the vehicle by retarding spark timing and by reducing air flow into the engine via an electronically controlled throttle. The engine control routine is entered if the average wheel speed of the driven wheels is above a predetermined threshold speed. Control of spark timing is performed by a Proportional-Differential (PD) control technique. The electronically controlled throttle is controlled by a Proportional-Integral-Differential (PID) control technique. The brake control routine operates to reduce the rotational speed of the driven wheel which has the highest rotational speed. The brake control routine is entered if one of the driven wheels has a rotational speed which is greater than a maximum desired speed and if the difference in speed between the driven wheels is greater than a maximum difference value.