The Alphabetical Files contain information that was used to compile data sheets on specific individuals. There are copies, abstracts, and transcriptions of census records, county court records, land office records, vital statistics, and tax records. There is also information Clay received from other researchers, correspondence, obituaries, Bible records, pedigrees and genealogical charts, published sources, pension records, and tombstone inscriptions.

The Locality Files contain much of the same types of information that is found in the Alphabetical Files, but are arranged alphabetically by Virginia county name, followed by other states.

The Subject Files include a variety of materials relating to the Clay family, most concerning Robert Young Clay's immediate ancestors. There are files related to his editing and updating of the Clay entry in Adventurers of Purse and Person, as well as Bible records, genealogical charts, letters, inquiries, and notes compiled by other Clay researchers, and early Clay genealogical compilations.

The Clay Family Society was formed in 2001 "to encourage research and foster understanding of the genealogy and history of all branches of the Clay family." This series includes minutes and agendas, financial reports, mission statements and by-laws, membership lists and applications, correspondence, mailing lists, and material relating to Clay's design of the Society's logo. There are also files of the Society's annual "gatherings," including those held in Williamsburg, VA, Lexington, KY, and Beckley, WV.

The Ballow, Escue, Kittrell, and Young Family Research Files contain much of the same types of information that is found in the Alphabetical and Locality Files, but were kept separate by Clay because of the amount of material on these four families. This series includes copies of the Ballew Family Journal published by the Ballew Family Association of America.

The Allied Families (A-Z) subseries also includes genealogical research on numerous families related to the Clay family. There is a substantial amount of material on the Cabaniss, Filmer, Green, Jenkins, Jones, Parker, Pride, and Watkins families.

The Notebooks, or binders, contain the final typed group sheets with supporting documentation that were compiled from the family research files listed above. There are three groups of notebooks, and there is a "key" or listing of them. There is also an explanation of the system Clay used in numbering each individual. Some of the notebooks contain an index at the beginning, and some of them are missing. It is not clear whether these were combined with, or superceded by, other notebooks, or integrated into the family research files.

The photographs contain images of Clay and allied family members, and are arranged alphabetically. There are also unidentified group photos, negatives, and photo albums. There are also numerous photographs of Clay's hometown of Dixon Springs, Tennessee, as well as homes and other buildings in Smith County, Tennesssee, and the University of Tennessee in Knoxville.

There are numerous card files that were kept by Clay to aid in his research, including indexes to his notebooks, descendants of specific individuals, Clay marriages, deaths, and tax records, and cards that were never typed in final form or filed.

There are various groups of microfilm in the collection, including issues of the Carthage Courier from 1913 to 1968, and deeds and wills for Smith and Sumner Counties, Tennessee. There are also copies of census records from the National Archives, and miscellaneous court records from other localities.