This article addresses the gradual introduction of arrangements for validation of non-formal and informal learning in Europe. While the debate on how to identify, assess and recognise learning achievements acquired outside formal education and training institutions has been going on for several decades, we can now observe that these approaches are becoming a practical reality in an increasing number of countries. The article pays particular attention to the characteristics of validation processes and how these can be compared to assessment and testing in the formal education and training system. The main part of the article addresses the actual developments in Europe. Three main groups of countries are identified; those were validation has been turned into a regular part of national qualifications systems; those countries where these practises are emerging, although still at a test and piloting stage; and those countries where validation is given low priority. The final part of the article addresses a series of challenges stakeholders trying to take forward validation. The article is based on extensive research coordinated by Cedefop and the European Commission in the period 2006-2007 in relation to the "European Inventory on validation of non-formal and informal learning". Carried out by ECOTEC, this inventory provides an updated overview over developments in this field. (Contains 7 tables, 1 figure and 10 footnotes.)