With contributions by numerous experts1. Magnetic Superconductors.- 1. 1 Introduction.- 1. 2 How The Problem of Magnetic Superconductors Originated.- 1. 3 Pairbreaking Effects Impurities and External Fields.- 1. 4 Impact of Ternary Rare Earth Compounds.- 1. 5 Antiferromagnetic Superconductors.- 1. 6 Ferromagnetism and Superconductivity.- 1. 7 Superconductivity and Competing Magnetic Interactions.- 1. 8 Concluding Remarks.- References.- 2. Systematics of Superconductivity in Ternary Compounds.- 2. 1 Review of Superconductivity in Ternary Compounds by Structure Class.- 2. 1. 1 Compounds with MT4B4 Stoichiometry.- a) Primitive Tetragonal CeCo4B4 Structure.- b) Body-Centered-Tetragonal LuRu4B4 Structure.- c) Orthorhombic LuRh4B4 Structure.- d) Other MT4B4 Structure Types.- 2. 1. 2 Orthorhombic LuRuB2 Structure.- 2. 1. 3 CeCo3B2 and Related Structures.- a) Hexagonal CeCo3B2 Structure.- b) Monoclinic ErIr3B2 Structure.- c) Hexagonal Ba2/3Pt3B2 and LaRu3Si2 Structures.- d) Other MT3B2 Variants.- e) Hexagonal ZrRuSi Structure.- 2. 1. 4 Primitive Cubic Pr3Rh4Sn13 and Related Structures.- a) Pr3Rh4Sn13 Structure.- b) Ternary Compounds Related to Pr3Rh4Sn13-Type Materials.- 2. 1. 5 Primitive Tetragonal Sc2Fe3Si5 Structure.- 2. 1. 6 Primitive Tetragonal Sc5Co4Si10 Structure.- 2. 2 Concluding Remarks.- 2A. Appendix: Tables of Crystallographic, Superconducting and Magnetic Data for 14 Classes of Ternary Compounds.- References.- 3. Critical Fields of Ternary Molybdenum Chalcogenides.- 3. 1 Overview of Experimental Results.- 3. 2 Summary of Theory.- 3. 2. 1 Ginzburg-Landau Theory.- 3. 2. 2 Microscopic Theory.- a) Isotropic, Weak Coupling Superconductors.- b) Strong-Coupling and Exchange Effects.- c) Anisotropy and Multiband Effects.- 3. 3 The Role of Impurities.- 3. 3. 1 Mo6Se8.- 3. 3. 2 PbMo6S8.- 3. 4 Anisotropy.- 3. 4. 1 MxMo6X8 Compounds.- 3. 4. 2 T?2Mo6Se6.- 3. 5 The Temperature Dependence of Hc2 and the Question of the Paramagnetic Limitation.- 3. 6 Compounds with Magnetic IlSF