Abstract The glass-forming regions in the Li2O–TiO2–P2O5, MgO–TiO2–P2O5, and CaO–TiO2–P2O5 systems have been determined. Homogeneous glasses were formed with compositions of less than 50 mol% P2O5 in all three systems. The largest quantities of TiO2 could be introduced into glass for compositions of 30 mol% P2O5. In compositions with more than 50 mol% P2O5 only a mixture of the glass and crystal was formed. With an increase in the TiO2 content, the density of the glass increased and the volume per mole of oxygen decreased. These results indicate that the TiO2 had been easily incorporated into the glass with compositions of lower P2O5 contents, contributing to the stabilization of the glass structure.