The Historical Science Files Subseries consists of a compilation of files on various sciences, scientists, and scientific pursuits. The bulk of it appears to have been maintained and referred to by Pendray during his tenure as the science editor at both the Herald Tribune and Literary Digest. Much of the material is printed and appears to have been provided to Pendray by a clipping service. Also included are press releases and a small amount of correspondence.

The Articles and Short Stories Subseries contains both fiction and non-fiction writings. The bulk of the documents are typed and annotated drafts though numerous published articles are included as well. A nearly complete run of Pendray's article and short story output is represented here. All of his fiction and non-fiction pieces included here relate in some way to rockets, rocket technology, or space exploration.

The Books Subseries includes both published editions of Pendray's books and documents created during the writing and publication process. Both his fiction and non-fiction works are included. The history of the 1939 World's Fair time capsule and Pendray's book about the capsule are well-documented. Papers documenting Pendray's involvement in the editing of The Papers of Robert H. Goddard, including annotated manuscripts and correspondence with publishers and Mrs. Goddard, are also well-represented.

The Speeches Subseries include Pendray speeches on both rocketry and public relations. The bulk of the rocketry speeches consist of different editions of Pendray's presentation entitled "The Conquest of Space." Pendray spoke on rocketry in a variety of venues, including schools, science clubs, and societies. His public relations speeches were often delivered in front of chambers of commerce and business leagues.

The Miscellaneous Subseries includes Pendray's correspondence with publishers and editors, notes for book proposals and ideas, and newspaper clippings of reviews.