Julius Berstl's correspondence has been divided up into Personal and Professional. The Personal Correspondence series includes letters to and from close friends, actors and actresses, people he knew from the theater, and fellow writers. While the letters sometimes discuss more professional topics, they have been placed under Personal because of their informal nature and because Berstl often knew these people personally. Personal Correspondence includes all topics and themes outside of the business side of Berstl's writing. The letters range from 1901-1975 and include picture postcards, both typewritten and handwritten notes, and discussions about writing, theater, and many more things.

The Professional Correspondence series contains letters that pertain to the business side of writing and theater; these are often typewritten, form based letters from publishers and theaters concerning Berstl's work. There are a great number of rejection letters from all the major publishers and theaters in both America and Germany, all of which Berstl had kept in a different box. These letters range from 1943-1975.

Every folder in both of these series has its own Scope and Contents note that gives an idea of all or at least a majority of the correspondence found within it, with individual dates and the key correspondents.