This review article addresses the currently available literature on twin screw granulation (TSG). TSG is an emerging technology rapidly gaining interest in the pharmaceutical industry as a method of continuous wet granulation. The control of the geometry of the granulator over the formation of granules and the mechanisms of granulation are discussed. Process parameters including liquid to solid ratio, binder viscosity, method of binder addition, screw speed and material-feed rate and their control of granule quality are analysed. The need for further understanding of granulation mechanisms and the interaction between screw elements is highlighted, as well as the difficulties in equating process parameters between different granulators to ensure product consistency across sites. TSG is a process with great potential for implementation into continuous processing lines but process understanding must be developed to ensure predictable consistent granule quality. (C) 2015 Elsevier B.V. All rights reserved.