Extensive data are collected and presented to test the coupled‐carrier equations and attending density‐switching criterion proposed to describe nonthermal threshold switching in amorphous semiconductors. The equations and switching criterion predict in magnitude and functional form a wide range of phenomena found in the off‐state, during the switching‐on, in the on‐state, and during the switching‐off of amorphous chalcogenide films. The critical temperature noted in a variety of experiments is identified as the elevated temperature at which the switching criterion is fulfilled thermally in the presence of a small field.