Some recent electrical, optical and photoconductive experiments are reviewed, and the information they provide on the localized state distribution is discussed. Experimental results for a range of a-Si specimens produced by evaporation and by glow discharge decomposition are correlated, and their density of state distributions, obtained from field effect experiments, are discussed. Suggestions are made concerning the possible nature of some of the states. Finally, localized states in some typical chalcogenides are considered.