In this work a thermodynamic assessment of the (LiF + NaF + CaF2 + LaF3) system is reported. For the thermodynamic modeling of the liquid phase, the classical polynomial model, and the modified quasichemical model were used in parallel and compared. The extrapolation to higher order systems was done according to the Toop mathematical formalism. Furthermore, differential-scanning calorimetry data of the ternary (LiF + CaF2 + LaF3), (NaF + CaF2 + LaF3), and the quaternary (LiF + NaF + CaF2 + LaF3) mixtures are presented. Good agreement between the experimental data and the thermodynamic assessment was obtained. (C) 2011 Elsevier Ltd. All rights reserved.