This chapter covers the advances made since 2003 in the development of catalysts that can control the stereochemical outcome of olefin metathesis reactions. Various enantioselective processes, such as enantioselective ring-opening/cross-metathesis (EROCM) and enantioselective ring-closing metathesis (ERCM), promoted by chiral Mo or Ru complexes are discussed. A more recent development has been the introduction of complexes that can deliver the (often) higher-energy Z-alkene products selectively (vs. the typically thermodynamically favored E-alkenes generated by previous catalyst systems). The mechanistic basis and utility of different Mo, W and Ru complexes that can be utilized to access linear or macrocyclic Z-olefins is detailed. In all cases, the advantages and shortcomings of different catalyst classes (e.g., Mo/W alkylidenes vs. Ru carbenes as well as different types within each system) and their symbiotic relationships are presented. Whenever possible, applications to synthesis of natural products are discussed to underscore utility.