Welcome to this special issue of the Annals of Operations Research. We are delighted to present you a selection of peer reviewed papers from the 12th International Conference on the Practice and Theory of Automated Timetabling (PATAT) that took place in Vienna, Austria, between the 28th and 31st of August, 2018. The PATAT conference series has been running biennially, apart from a three-year gap between 1997 and 2000. This special issue represents our sixth post-conference volume of papers in the Annals of Operations Research.

The PATAT series serves as a multi-disciplinary forum for all aspects of automated timetabling research. The 12th PATAT conference was held in TU Wien’s Faculty of Informatics right in the center of Vienna. Eighty-five delegates from 21 different countries around the world joined the conference. The programme featured 54 presentations, including 4 plenary papers, 2 invited tutorials, 21 full papers and 27 extended abstracts. An itinerary of excellent plenary talks were given by Johannes Gärtner, Louis-Martin Rousseau, Hana Rudová and Pascal Van Hentenryck. We were also fortunate to have outstanding invited tutorials by Jeffrey Kingston and Andrea Schaerf.

We would like to express our gratitude to the Organising Committee, TU Wien and the wide range of dedicated individuals who made the 12th PATAT conference such a success, including Juliane Auerböck, Emir Demirović, Lucas Kletzander, Florian Mischek, Tommaso Urli and Felix Winter. Additionally, we thank the PATAT Programme Committee for their hard work in generating such rigorous and thorough reviews. We also owe a debt of thanks to the Steering Committee for their ongoing work in supporting the successful continuation of the series. Finally, we extend our gratitude to all the authors and delegates for their contributions to the conference.