Abstract: A knit sock, especially for jogging or other athletic activity, has a foot portion consisting of a first inner layer or ply disposed inside a second outer layer or ply. The first ply of the foot portion has an inner surface adapted to contact the skin formed principally of yarns having high frictional characteristics, high thermal conductivity, and low moisture regain (hydrophobic). Its opposed surface is formed principally of yarns having relatively low frictional characteristics. The second ply has an inner surface which has low frictional characteristics and its outer surface is formed of yarns having relatively high frictional characteristics and high moisture regain (hydrophilic). The latter surface may also be formed with terry loops to enhance its shock-absorbing construction as well as to increase its moisture absorbing capacity.