A new differential thermal analysis (DTA) experimental method has been developed to determine the critical cooling rate for glass formation, Rc. The method, which is found especially suitable for melts that, upon cooling, have a small heat of crystallization or a very slow crystallization rate, has been verified using a 38Na2O-62SiO2 (mol%) melt with a known Rc (not, vert, similar19 °C/min), then used to determine Rc for two complex lithium silicate glass forming melts. The new method is rapid, easy to conduct and yields values for Rc that are in excellent agreement with the Rc values measured by standard DTA techniques.