ABSTRACTA new criterion γ, defined as Tx/(Tg+Tl) (where Tx is the onset crystallization temperature, Tg the glass transition temperature and Tl the liquidus temperature), has been proposed for glass formation in bulk metallic glasses (BMGs). The interrelationship between this new parameter and glass-forming ability (GFA) was elaborated and discussed in comparison with other established criteria. It was found that the new criterion γ had a much better correlation with GFA than other established parameters. An approximation of the critical cooling rate for glass formation was also formulated and evaluated in the light of this new parameter.