ARS MATHEMATICA CONTEMPORANEA Bojan Mohar's 60th Birthday In the frame of the Leoben-Ljubljana Graph Theory Seminar 2016 (Judenburg, Austria, September 25-28, 2016) a special session was organized to celebrate Bojan Mohar's 60th birthday. Bojan Mohar is an outstanding representative of the Slovenian graph theory school. In 1985 he obtained his PhD under the guidance of Toma Pisanski. Since 2005 he has been holder of a Canada Research Chair in Graph Theory at Simon Fraser University, Vancouver, Canada. He continues to be deeply involved in research at the Faculty of Mathematics and Physics, University of Ljubljana, Slovenia, and at the Institute of Mathematics, Physics and Mechanics, also in Ljubljana. Bojan Mohar is a world recognized mathematician who works in the area of graph theory. This year he was awarded the Euler Medal for the year 2010. Let us quote a part of the citation for this award: "Bojan Mohars outstanding research and leadership over a period of thirty years place him as one of todays foremost discrete mathematicians worldwide. His deep and important contributions have dramatically improved our understanding of the structural properties of graphs. His research spans many areas, including topological graph theory, graph minors, infinite graphs, spectral graph theory, algebraic graph theory, and computational geometry." To this citation we add a couple of specific achievements of Bojan. His monograph "Graphs on Surfaces" (Johns Hopkins University Press, 2001), written jointly with Carsten Thomassen, is the central contemporary work on topological graph theory. Among numerous editorial duties Bojan Mohar serves as one of the two Editors-in-Chief of the renowned Journal of Combinatorial Theory Series B. He is also a recipient of Slovenian national awards; in particular, in 2009 he became an "Ambassador of Science of the Republic of Slovenia". Happy Birthday, Bojan! Sandi KlavZar Associate Editor xxiii