Electrical conductivity of heterocyclic aromatic ladder polymers, BBL and BBB, is studied by doping with Lewis acid, protonic acids, and potassium. The doping of sulfuric acid and potassium naphthalide was found to be the most effective; with sulfuric acid, sigma equals 2 OMEGA ** minus **1 cm** minus **1 for BBL and sigma equals 1 OMEGA ** minus **1 cm** minus **1 for BBB, and with potassium naphthalide, sigma equals 1 OMEGA ** minus **1 cm** minus **1 for BBL, corresponding to a 12-order-of-magnitude increase in the conductivity. An enormous increase in thickness and weight of the doped films is attributable to the planar layered structure.