Previously published data of three-phase fluidization were correlated to develop a new empirical correlation for predicting bed voidage in gas-liquid-solid fluidized beds. The proposed correlation model, when used in conjunction with any suitable two-phase model for bed voidage, can serve as a correlation for bed voidage in both two- and three-phase fluidized beds. It describes the bed expansion and contraction phenomena observed during fluidization and is valid even as the superficial gas velocity approaches zero. A new criterion for quantifying the bed expansion and contraction phenomena based on this empirical model is derived and is also discussed in this paper.