There are many interesting stereochemical aspects of dicoordinate sulfur compounds, such as the crown conformation of the common allotrope of elemental sulfur, S8, the dihedral angles of various disulfides, the variation in the S-S bond lengths in oxypolysulfane rings, the structures of cluster molecules, such as ferredoxin or rubredoxin, and the hypervalent interaction of the sulfur atoms which are sandwiched between nucleophilic heteroatoms to form linear arrangements. However, stereochemistry of the sulfur atom itself is of major importance in the chiral three-coordinate sulfur species, sulfoxides, R-S(O)R′, sulfilimines, R-S(NY)-R′, and sulfonium salts, R3S+. These compounds and several of a higher coordination number will be discussed here.