Liquidus temperatures (TL) were measured, and primary phases were determined for 50 (from an initial test matrix of 76) compositions within the Al2O3–B2O3–CaO–Na2O–SiO2glass-forming system and its constituent ternary subsystems. Strong linear correlations have been found between composition andTLfor melts within the same primary phase fields. TheTLand primary phase data are being used to develop and refine a modified associate species model (ASM). The impacts of Fe2O3, Li2O, NiO, ZrO2, Cr2O3, ZnO, and MnO additions on theTLof two baseline glass compositions are reported. These data are intended as benchmarks for further expansion of the ASM or other silicate melt solution models of nuclear waste glasses.