Rare-earth aluminates having the general formula LnMAl11O19 with Ln3+ = La, Pr, Nd, Sm, Eu, Gd, and M2+ = Mg, Ni, Co, Mn, Fe have been synthetized. This paper is devoted to mixed compounds of the series La1−xNdx Mg Al11O19 of which large single crystals have been obtained by the flame fusion method. A full refinement of the pure lanthanum compound (x = 0) having a quasimagnetoplumbite structure has been performed (final R = 0.039). Spectroscopic investigations of the (La, Nd) aluminate have allowed the measurement of fluorescence yield and lifetime of Nd3+ in the host lattice as a function of the neodymium content. Additional results have been obtained on the magnetic anisotropy, from susceptibility measurements performed on the Nd3+ aluminate in the temperature range 4–300 K.