The Catherine Byron Letters is an edited and annotated collection of letters mostly exchanged between Catherine Byron, the mother of the poet, and her solicitor John Hanson. The importance of this correspondence was first established by Doris Langley-Moore in Lord Byron: Accounts Rendered (1974), which documents the poet's finances from the time of his birth. Since then the letters have been used extensively by Megan Boyes in My Amiable Mamma: A Biography of Mrs. Catherine Gordon Byron (1991) and by J. V. Beckett and Sheila Aley in Byron and Newstead: The Aristocrat and the Abbey (2001). For this project I have transcribed and edited the portion of Catherine Byron's correspondence now in the John Murray Archives at the National Library of Scotland, amounting to 92 letters which are here reproduced in their entirety. While some are familiar letters, most of the correspondence is concerned with the business of providing for the young poet's education at Harrow and at Cambridge, paying off his mounting debts, managing the Newstead Abbey estate, and pursuing the lawsuits which entangled the family finances. I have edited the transcribed letters using the TEI (Textual Encoding Initiative) markup language, adding optional punctuation where necessary to clarify the sense as well as headnotes and additional annotations for personal names, places, and technical terms where they require elucidation. The resulting machine-readable XML documents have been made into a website on which I have collaborated with Professor Radcliffe.