Motion control footwear is a common technology in running shoe designs. The function of motion control footwear is mainly to reduce excessive rearfoot pronation in runners for injury prevention. Because erratic rearfoot kinematics may affect proximal joints by the linkage of human kinetic chain, the functions of motion control footwear may not only be confined to kinematic control. The functions of motion control footwear are not well explored and understood. This book explores functions of motion control footwear in runners with excessive rearfoot pronation.