The second edition of the International Test Commission Guidelines for Translating and Adapting Tests was prepared between 2005 and 2015 to improve upon the first edition, and to respond to advances in testing technology and practices. The 18 guidelines are organized into six categories to facilitate their use: pre-condition (3), test development (5), confirmation (4), administration (2), scoring and interpretation (2), and documentation (2). For each guideline, an explanation is provided along with suggestions for practice. A checklist is provided to improve the implementation of the guidelines. [This paper was written by the International Test Commission (ITC), including Dave Bartram, Giray Berberoglu, Jacques Grégoire, Ronald Hambleton, Jose Muniz, and Fons van de Vijver.]