The results of theoretical investigations of the electronic structure of BaF2 and LaF3 crystals and BaF2–LaF3 complexes without and with La impurity are presented. Changes in the structure of the state density, electronic spectrum, and effective charges caused by defects are analyzed. It is demonstrated that the NNN position of the [La3+ Fi −] defect in BaF2 is more stable than the NN position.