The incorporation of Nd ³⁺ in the ferroelectric fluoride BaMgF ₄ crystal is investigated for its potential application as self-frequency-converter solid state laser. Low temperature high-resolution optical spectroscopy shows that Nd ³⁺ is located at two well distinguished sites referred as A and B. The whole set of energy levels in the excited ⁴ F _3/2 , ⁴ I _11/2 , and ground ⁴ I _9/2 states are identified for both Nd ³⁺ sites and their crystallographic location in BaMgF ₄ lattice is discussed. The radiative lifetime of the ⁴ F _3/2 metastable laser level is obtained to be 1430 and 800 μ s for site A and B, respectively, and the luminescence quantum efficiency of the ⁴ F _3/2 metastable state for the dominant A site is 87%. The possibility of annihilating the contribution of the B site in the optical spectrum is demonstrated by means of the incorporation Na ⁺ into the crystal.