AbstractIn most low‐strength applications, plastics offer cost, maintenance, and density advantages over metals. Major deficiencies of plastics, however, are low thermal and electrical conductivities. Various studies have dealt with these problems, and it has been found that thermal conductivity and electrical conductivity can both be increased by the addition of conductive fillers to the polymer. The two parameters that most significantly affect the increase in conductivity of the resulting composite are volume loading of filler and filler shape. Fibrous conductors improve conductivity much‐more significantly than spheres, flakes, or irregular particulates. The effect of fillers on thermal and electrical conductivities is not the same. The maximum increase in thermal conductivity that can reasonably be expected over the base polymer is 100:1. Electrical conductivity, on the other hand, can be increased by a factor of 1015. One particularly attractive technique for increasing the electrical conductivity of polymers is electroless plating of metals onto glass fibers which are then incorporated into the polymer. Such a composite can he made electrically conductive with as little as 6 volume percent metal.