To evaluate the thermal stability of oxide glasses against crystallization, a new criterion based on the length of induction period of crystallization is suggested. It is discussed that the end of the induction period of crystallization corresponds to the moment where the crystallization nuclei have already been formed and the intense growth of crystals starts. Three glasses with the composition of Li2O-2SiO(2) (a), Li2O center dot 2SiO(2)-0.03TiO(2) (b) and Li2O center dot 2SiO(2)0.1TiO(2) (c) were prepared and the validity of the criterion was tested by applying it to these glasses. The results indicate that the new criterion enables to discriminate among the thermal stabilities of the silicate glass samples. It can be expected that it can be employed generally for the assessment of the thermal stability of any glass against crystallization, including metal and organic glasses. (c) 2004 Elsevier B.V. All rights reserved.