Conductivity in impurity bands is observed in gallium arsenide at low temperatures. The impurity banding phenomena observed inn‐andp‐type crystals are markedly different due to the wide divergence in their effective masses. In the temperature interval where the crystal conductivity is determined by conduction in the impurity band, resistivity ofn‐type material decreases with increasing magnetic field.The temperature dependences of carrier mobility indicate that at low temperature the impurity ions play the dominant role of the scattering centers. In order to investigate scattering processes more thoroughly, studies were made of the thermomagnetic Nernst‐Ettingshausen effects which are very sensitive to the scattering mechanism. It was found that, in the case of nondegenerate specimens at low temperatures, scattering by impurity ions dominates, and at high temperatures by acoustical lattice vibrations; scattering by acoustical lattice vibrations becomes dominant even at low temperature in specimens of high degeneracy. Scattering was also investigated in indium arsenide and indium antimonide.