This Diary records Alleyn's daily financial accounts for every aspect of his private life and professional career, including the costs of food, clothing, medicine, and travel, property and building purchases, court and legal expenses, salaries for various employees and interaction with a variety of government and religious officials, tradesmen, and ordinary people. Also included are itemised costs for the foundation and maintenance of Dulwich College, Chapel and Almshouses, as well as festive birthday, Christmas and New Year's celebrations with the poor.

More broadly, the Diary provides a list of Alleyn's daily actions and movements across the social and political spectrum, from meetings with James Villiers, the favorite of King James I, to property development with middle-class entrepreneurs to the supervision of gardeners, carpenters, and a variety of household servants, provding an unusually full view of life in early modern England. Alleyn's Diary also documents his frequent trips to London, complete with the routes taken and the lists of pubs visited, offering a virtual map of some areas of the city and its environs. Most notably, Alleyn is an eyewitness to a wide range of the major events of the period, including the death and funeral of Queen Anne and the destruction of Whitehall Palace by fire.

William Young produced an edition of the Diary in Volume 2 of The History of Dulwich College (Edinburgh: Morrison &Gibb, 1889). A new edition of the Diary is being prepared by S. P. Cerasano and Grace Ioppolo for Oxford University Press. Also see the Digital Essays.