Series I. Personal papers (education, early career, and personal interests) includes class notebooks from a fine arts class at the University of Pennsylvania School of Design and Tehon's diploma from the same program. The notebooks are illustrated throughout with Tehon's sketches related to the lectures. Information about the Louis Comfort Tiffany Foundation scholarship can be found in the collection, however there is no documentation of her year in Europe. A note from Tehon in 2003 indicates that her year abroad was the most valuable portion of her education. There is a small group of notes on lectures, design, and production from the mid 1950s, but it is unclear if these notes were taken in courses or in her day-to-day learning at a job. This series also includes a few items documenting Tehon's career before she began working at Dial Books for Young Readers. There are also some family records relating to her father and brother, as well as notices and correspondence at the time of her marriage to Stephen Thiras. This series includes a few tributes and memorials that she wrote for her friends. Of particular interest may be the tributes written about Tehon following her death in 2012 which provide a glimpse into the way those who knew her felt about her and her influence on their careers and the children's book publishing sphere.

Series II. Correspondence is arranged alphabetically by sender. There are very few correspondents with a significant number of letters to or from Tehon; instead, these letters illustrate Tehon's large circle of friends and professional acquaintances. It appears that, in most cases, relationships that began professionally often turned into friendships and therefore, no attempt was made to distinguish correspondence created at Dial from her personal correspondence. Researchers should be aware that correspondence relating to book projects that was originally kept by Tehon with papers relating to a specific project can be found in Series V. Book projects. A number of handmade holiday cards can be found throughout the collection as well as letters with extensive illustrations by the writers.

Series III. Dial Books serves as a small window into Tehon's career at Dial Books for Young Readers. Tehon's calendars show the complexities of her job as well as the schedules for publishing. These calendars also provide an excellent snapshot of the day-to-day workings of a book designer and art director. Of interest in this series are the notes regarding talks and workshops at events in which Tehon participated. Some of the talks include full narratives while others are merely notes; but they are indications of the influence Tehon had on the field. Event notes and memos at the time of her retirement from Dial in 2001 can be found in this series; however, researchers should also consult Series II. Correspondence for individual notes and letters written to and from her regarding plans for retirement and freelance work.

Series IV. Collected material on artists, authors, illustrators, publishers, publishing, etc. is arranged in two subseries: A. Artists, authors, illustrators, museums, publishers, etc. and B. General information on publishing, children's books, etc. The first subseries includes articles presumably clipped by Tehon about specific people or occasionally museums or publishing companies; exhibition notices or mailings; lists of artists; handwritten notes about artists; promotional mailings; bookseller catalogs; resumes of artists; and a few submissions or samples of writing or illustrations. It is unclear if Tehon worked with all the people whose information she collected or if she was looking for potential artists, authors, and illustrators. The folder of notes on artists, authors, and illustrators contains notes that occasionally look like phone reference checks or interviews including comments and/or possible projects. Other than the folders containing notes and lists of artists, very little of the material in this subseries is unique; instead this material was mass-produced. The aggregation of this material, however, provides a "who's who" of children's publishing from the 1970s to the early 2000s. The second subseries includes articles about children's books and publishing; copyright and fair use; fonts, graphics, and typography (an area in which Tehon was deeply interested, according to tributes following her death); and printing. There are numerous reviews of children's books as well a number of covers of magazines and journals. This group of material shows Tehon's interest in the field and, to a limited degree, her own research scope.

Series V. Book projects is arranged by publishing company. The bulk of the material in this collection appears to have resulted from Tehon's freelance work rather than her career at Dial; and many of the projects that were produced by Dial were undertaken after Tehon retired in 2001. Many files in this series are extremely rich, containing correspondence, drafts of illustrations, dust jacket design, F&Gs (folded and gatherings), mockups, notes, page proofs, and text dummies. Projects which are most fully documented are: Dear Mili, Hamlet, The Juniper Tree, King Grisly-Beard, Noah's Ark, The Old African, and Parsifal. In many cases, these files provide an almost start-to-finish view of the design of a children's book, and Tehon's notes (almost always on post-it notes) show her methodology in working with authors, illustrators, and publishers. Peppered throughout the files are letters to Tehon from illustrators (notably Jerry Pinkney, Maurice Sendak, William Steig, and Margot Zemach). Researchers interested in a particular project should also consult Series VIII. Audio, video, and computer files to ascertain if digital files exist.

Series VI. Artwork includes drawings, sketches, paintings, photographs, and woodcut prints by both Tehon and others. First, this series includes artwork by Tehon, an accomplished artist. Researchers will find a number of Christmas cards that she created and printed; drawings, sketches, paintings, a few photographs, and sketchbooks. The bulk of the artwork created by Tehon is pencil sketchings: many life drawings, but also still life drawings and landscapes. A copy of her sketchbook from an anatomy class is particularly indicative of Tehon's artistic abilities. Also in this series is artwork by others, largely the artists, authors, and illustrators with whom she worked in her career as art director and book designer. Researchers will find original artwork, as well as few prints, frequently inscribed to Tehon with notes.