This paper describes a fuzzy logic (FL) approach to the design, implementation, and tuning of an expert knowledge-based TCS for a four-wheel drive vehicle. Military and commercial mutual interests in TCS technology are highlighted as the underlying motivation for this government, industry, academia cooperative program. Coordinated parallel efforts to model the TCS equipped vehicle and to perform basic on-vehicle TCS experiments provided additional information to augment the knowledge obtained from a study of commercial TCSs and the tire traction literature. The general traction control problem is discussed along with the hardware considerations for a TCS. The design and integration of the resulting FL-based TCS are described along with a representative sample of the test results documenting the system's performance.