This proceedings volume contains a selection of invited and contributed papers of the 9th International Workshop on Sulfur Metabolism in Plants, which was hosted by Heinz Rennenberg, Albert-Ludwigs-University Freiburg and was held at Schloss Reinach, Freiburg-Munzigen, Germany from April 14-17, 2014. The focus of this workshop was on molecular physiology and ecophysiology of sulfur in plants and the content of this volume presents an overview on the current research developments in this field.