This series consists of three subseries: Correspondence, Karl Weigl Memorial Fund, and Other Papers. Correspondence is arranged alphabetically by name, with incoming and outgoing letters interfiled. All correspondence in this series dates from after Karl's death. A small amount of earlier correspondence of Vally is present is Karl Weigl's Correspondence (Series II); correspondents appearing in both series are cross referenced. Many letters in this series relate to the Karl Weigl Memorial Fund, including solicitations of initial support in 1966, subsequent appeals for donations, and establishment of other performance and recording funds. Other letters concern additional efforts to promote Karl Weigl's music and the disposition of his music manuscripts and other papers. Also present are letters concerning Vally Weigl's music, her later life, and the Weigl family. Correspondents include Kurt Adler, Ernst Bacon, Pablo Casals, Sam Denison, Ira Arthur Hirschmann, Hans Moldenhauer, Maria Weigl Piers, Daniel Sternberg, Jean Starr Untermeyer, Ruth T. Watanabe, John Weigl, and Florian Wiefler.