The collection provides a detailed account of Gillilan's life, and of Methodism in Ohio and Utah. The most significant items in the collection are Gillilan's thoroughly kept diaries. In addition, he was a meticulous keeper of scrapbooks, collecting many articles about Methodism and religion in his time. He was also a published author, and copies of many of his published poems and essays are present in the collection. It seems that he sometimes wrote under the pseudonym Strickland Gillilan. It is possible that this is a family member. In his collection are also present two threatening letters. One dates from 1886, and is from Gillilan's time in Tooele, Utah. It relates to issues of polygamy and Mormonism. The other is less specific, but threatens Gillilan' s "precious throat." Gillilan's papers contain approximately 2000 sets of sermon notes, numbered from 5 to 2394. The system by which these numbers were assigned is unknown. One of Gillilan's diaries, the largest, contains several pages of what seem to be land ownership claims and mining records. He may have obtained this book, already used, and subsequently used it for his journal. Another of his diaries contains several pages written in a substitution code, and several more in shorthand. The key to Gillilan's code is in the Diaries: General File. Many of the books and documents are fragile, and should be handled with extreme care.

Record types within this collection include sermons, addresses, clippings, notes, note cards, orders of worship, and program materials. Most of the collection consists of sermons and addresses delivered by Arnold to a wide variety of community and church groups. These are mostly handwritten and in outline form, although a few are complete typewritten manuscripts. Topics include Biblical themes, challenges of Christian living, national and patriotic subjects, liturgical and secular holidays, and Sunday School lessons. Many were delivered to church services and church groups in Ohio and neighboring states; others were addressed to a wide variety of community groups. Among the organizations that benefited from Reverend Arnold's wit were the Ohio Farm Bureau, 4-H Club, Rotary Club, General Conference of 1933, and the Otterbein Guild. The clippings and notes are closely related to Arnold's sermons and addresses. Also included in this collection are some program materials relating to Arnold's work with the Evangelical United Brethren Sunday school publications, as well as a few orders of worship from his ministerial and speaking career.

This collection primarily documents the work and ministry of the Evangelical Church's annual conferences and local churches from the middle nineteenth century to the middle twentieth century. To a lesser degree there are records that reflect the ministry of the general church as well. There are other records that pertain to filial denominations such as the Evangelical Association, United Evangelical Church, Church of the United Brethren in Christ (United Brethren Church), and the Evangelical United Brethren Churches are also found in this collection. Leedy was an avid collector of church related information so that the topical landscape of this collection is broad enough to cover information ranging from local church ministries and histories to denominational theological beliefs and social concerns. Most of the paper records center on church work in the Ohio region though not to the exclusion of other geographic areas within the continental United States and Germany. All in all this collection provides a nice overview of the diversified life within the Evangelical tradition and is an excellent resource for those who wish to understand more fully the Evangelical Church's historical influence within the ongoing traditions of United Methodism.