Twenty years have passed since the announcement of the September 2015 project Mapping European Butterflies (MEB) in 1995. Seven years have passed since the first phase (MEB-1) could be completed using innovative project-specific methods. The Distribution Atlas of European Butterflies was published in 2002. The MEB data bank contained then about 250,000 data records contributed by about 250 recorders from all over Europe. It was the first computer-aided distribution atlas of butterflies of any continent ever published. The late C.M. Naumann praised the Atlas as “a milestone in the history of European lepidopterology” – a commendation to be proud of. Nine years later the second phase of MEB (MEB-2) was completed and the Distribution Atlas of Butterflies in Europe based on about 650,000 data records appeared in 2011. In spite of the generally positive echo and contrary to most co-authors, the leading author was far from happy. Blessing in disguise: The Atlas was completely sold out in about one year. The commercial success helped to open the way to the present Distribution Atlas of European Butterflies and Skippers completing the third and possibly the last phase of Mapping European Butterflies (MEB-3).