The current book comprises a study on twin roll casting (TRC) of AZ31 magnesium alloy. TRC process is an attractive manufacturing process in terms of sheet production. This process incorporates casting and hot rolling in one process. In the current book, a review of the past studies on the TRC of steel, aluminum and magnesium alloys is presented followed by developing a thermal-fluid-stress model to simulate the thermo-mechanical behavior of the AZ31 twin roll cast strip. The process was studied in terms of temperature distribution and stress-strain development in the cast strip, roll separating force, solidification cooling rate and.... The effect of roll diameter was also studied to develop a scale-up model. The results were then correlated to conditions which lead to inverse and center-line segregation formation to develop process maps. Using process maps, the optimum casting conditions to produce high quality magnesium sheets are determined.