The collection includes correspondence 1898-1930, notebooks, newspaper cuttings, lectures and study notes, transcripts and facsimiles of documents, publication proofs, as well as pamplets 1700-1900 and original material dating from 1624. There is a particular emphasis on the areas of Hay Fleming's own research, including the history of St Andrews and Fife, Mary Queen of Scots and scottish ecclesiastical history.
Some notable original items include 19th century street games and rhymes of St Andrews, St Andrews examination roll, 1719-52, bonds and financial papers, 18th-19th centuries; Strathkinness congregational roll, 1816-1890; Madras College magazine, 1950-53; Sermons of William Tullideph, 17th century; Covenanter sermons, notebooks etc. 17th-18th centuries; Memoirs of Bishop Guthrie, 1681; Music manuscript, 1722; volumes relating to the trades in St Andrews: wrights 1624, tailors ca. 1661-87, weavers and tailors, 1751-1850; engraving of St Andrews cathedral, 1776.