The lattice mismatch for (112) copper and silver chalcopyrite films grown on (0001)CdS substrates is calculated for the different chalcopyrites, for different degrees of substrate surface roughness, and for different compositions of the solid solutions of the type I-III-VI2-x-VIx. It is shown that the mismatch can be reduced to zero only if γt = 2, as it does for CuInSe2-xTex, and if the CdS substrate is smooth. It is also shown that, of all these chalcopyrites, the CuInSe2 has the best lattice match with the CdS. The misorientation between equivalent planes, and the lattice distortion, which is due to atoms across the interface occupying different atomic positions, is discussed.