How would you……describe the overall signifi cance of this paper? Recently, technologies for twin-roll casting have been widely developed to effi ciently fabricate the lightweight Mg alloy sheets that are quite attractive for numerous weightsensitive applications. This paper reviews the recent progress in the twin-roll casting of Mg alloys with technologically critical issues and alloy development activities. …describe this work to a materials science and engineering professional with no experience in your technical specialty? This paper reviews the recent progress in the twin-roll casting of Mg alloys, focusing on the processing aspects that have close relations to the solidifi cation behavior of Mg alloy strips. It also deals with the attempts to develop new Mg alloys utilizing the metallurgical advantages attainable by this novel casting process, such as the fast solidifi cation rate and extension of solid solubilities of alloying elements. …describe this work to a layperson? This paper reviews the recent progress in the twin-roll casting of Mg alloys, which can effi ciently produce lightweight Mg alloy sheets. At present, there are numerous research activities in the world to develop processing technologies for twin-roll casting of Mg alloys, aiming at the widespread applications of Mg alloy sheet products especially in the automobile industry. Recently, technologies for twin-roll casting have been widely developed to effi ciently fabricate the lightweight Mg alloy sheets that are quite attractive for numerous weight-sensitive applications. This paper reviews the recent progress in the twin-roll casting of Mg alloys, focusing on the processing aspects that have close relations to the solidifi cation behavior of Mg alloy strips. In addition, recent attempts to develop new Mg alloys utilizing the metallurgical advantages attainable by this novel casting process are also presented.