The CaO-Al2O3-SiO2 system has been assessed with the CALP-HAD technique, based on recent assessments of its binary systems. A new species AlO2-1 was introduced for modeling liquid Al2O3. The ternary liquid phase was described using the ionic two-sublattice model as (Al+3, Ca+2)(p) (AlO2-1, O-2, SiO4-4 SiO20)(Q). The available experimental data were critically examined and a self-consistent set of thermodynamic descriptions was obtained. Various phase diagrams and property diagrams, including isothermal sections, isoactivity lines, and a projection of the liquidus surface, are presented. Information on viscosity seems to support the use of the AlO2-1 species.