This 100th anniversary volume of Bibliotheca Lichenologica, pays tribute to the diversity in lichenology. Multiple, cosmopolitan aspects of the research on lichens in its breadth are reflected in the large variety of subjects covered in 18 chapters by 37 authors from 13 countries. The chapters document recent developments in taxonomy, phytogenetic analyses, phylogenetic research, fl oristic studies and lichen ecology, and - again - a large number of newly described taxa, keys to the identifi cation of Usnea, and details of current analytical work. A personal review by Ingvar Kärnefelt of past and present contributors to lichenology. His biographical sketches provide a good measure of the multi-faceted nature of lichenology and of the expertise involved in its development, paying tribute to Bibliotheca Lichenologica's anniversary. The volume was carefully edited by three prominent and active members of the lichenological community, Arne Thell, University of Lund, Sweden, Mark R. D. Seaward, University of Bradford, United Kingdom, and Tassilo Feuerer, University of Hamburg, Germany.