Wet fluidization occurs when small amounts of liquid are injected into a fluidized bed, causing liquid bridges to form between particles. These liquid bridges create complex interparticle forces with cohesion and dissipation due to surface tension and viscosity, respectively. Liquid bridging leads to significant changes in hydrodynamics, causing agglomeration of particles and in some cases defluidization. This article reviews prior work to understand wet fluidization, including microscale studies of individual liquid bridges and experimental and modeling techniques to understand liquid transport and changes in hydrodynamics in fluidized beds. The various effects on fluidization which have been observed are discussed, including efforts to map behavior into regimes based on liquid and operating parameters. This article concludes with an outlook on the future of wet fluidization research, highlighting major open questions in the field and important future studies. (C) 2017 Elsevier B.V. All rights reserved.