Correspondence, received and sent, between Ivan Mestrovic and other artists, galleries and museums, foundries, architects, prospective clients, U.S. government officials, Yugoslav emigrants, and friends who remained in Yugoslavia after World War II. Subjects covered in the letters fall into two main categories, Mestrovic's art and events in Yugoslavia, especially as they were affected by World War II. The letters concerning his art discuss his approach to his work, the wishes of clients who are commissioning work, instructions for casting and shipping sculpture, his exhibitions and publications, and awards Mestrovic received.

The letters concerning Yugoslavia and World War II discuss the history and politics of Croatia, Serbia, and other Yugoslav republics, the events of World War II as they affected his family and friends, the status of the property and artworks Mestrovic left behind when he fled Croatia during World War II, the whereabouts and welfare of friends and family in Yugoslavia, in particular Cardinal Aloysius Stepinac, and pleas for financial and political assistance from people still in Yugoslavia and those who had emigrated.

Although most of the correspondence was written after Mestrovic left Yugoslavia during World War II, the papers do include photocopies of earlier letters, primarly from 1925 to 1927, concerning exhibitions of his work in the United States and his visit to this country. Many of these letters are the work of Petar Mestrovic, Ivan's brother, who acted as an unofficial agent for Ivan while the artist's work was being exhibited inthe United States.