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 an…