Most of Fr. Thro’s research was focused on manuscript studies. A large part of the material in this collection consists of his work on the critical editions of medieval manuscripts, most notably John Dymsdale’s commentaries on Aristotle’s works. A small part of his manuscript research was published in Manuscripta. Another portion of his research was unpublished, but is in a publishable form – he planned to publish the work in Manuscripta, but it was left undone due to Fr. Thro’s death and the death of Dr. Charles Joseph Ermatinger, who worked with him.

Another significant part of this collection documents and records Fr. Thro’s academic activities and his religious and philosophical education. Notable materials include papers related to the Danforth seminar series, which were summer seminars for teachers on the topic of religious education and its relation to other subjects like natural science.

Other materials in this collection include Fr. Thro’s master’s thesis and dissertation, and a copy of one of his books that was co-written with Fr. Robert Henle. Additionally, the collection includes a series of materials published by other scholars and sent to Fr. Thro, as well as materials related to his life as a priest, his correspondence with family members and associates, photographs, and personal documents.