There have been many studies on the magnetic semiconductor CdCr2Se4which report the large effect of magnetic ordering on its transport properties in the Ga- or In-substituted material. The substituted material shows N-type conduction compared to P-type conduction in the unsubstituted. The electrical resistivity has a maximum near its Curie point, and then decreases with a further increase of temperature. The material has a large negative magnetoresistance effect at its Curie temperature. The present paper reports the transport properties of the material with greater substitution than the previous works. The purpose of this work is to provide the necessary information for the application of the combined effect of magnetism and conduction in ferromagnetic semiconductors. For additional details, see Digests of the 1972 Intermag Conference (available from IEEE Headquarters).