Intermetallic compounds constitute a very important class of materials for electromagnetic applications. In this article, some important materials and applications are discussed in the following areas: (1) magnetic, magnetoresistive, and magnetostrictive applications; (2) superconductor applications; (3) semiconductor and optical applications; (4) magneto-optical applications; and (5) thermoelectric applications. Emphasis is placed on materials that are important in existing devices and applications or show promise for future applications. The interested reader should consult the reviews in Westbrook and Fleischer's book, and the many references contained therein, for further information.