The volume covers alloys and intermetallic compounds of thorium with metals of main groups I to IV as well as related ternary and quaternary alloys. It is the first comprehensive and critical treatise on this topic. The physical properties of ThBe13 have been studied in some detail in order to compare them with those of the heavy fermion compound UBe13. The Th-MG system is of interest for the metallurgy of Mg, since small amounts of Th improve the mechanical strength of Mg and some of its alloys. Detailed information is available on the Th-AI system which is complicated by several intermediate binary phases. Several years ago, this system had attained some technological interest when Th-AI alloys were considered as a potential fuel in thorium breeder reactors. Other Th-main group intermetallic systems are more of scientific than of technological interest. The phase relations in these systems were not elucidated until the 1980s. Numerous ternary alloys consisting of thorium, a metal of main groups I to IV, and a third metal are described. Recent interest has focused on some ternary compounds related to the Th-AI and Th-Sn systems, e.g., THAI8Fe4 and ThSnM (M = Ni, Co, Pt).