Dragos Iliescu has been working with tests, testing, and test adaptation for more than twenty years as both a scientist and entrepreneur. He founded or contributed to several test publishers in Eastern Europe and with test adaptation publishers and firms all over the world. He co-edited the ITC Handbook of Testing and Assessment (2015) and is presently President of the International Test Commission (ITC), as well as associate editor of the European Journal for Psychological Assessment. This is his first monograph.