Harwinton Fair, originally known as Harwinton Cattle Show and Fair, is the yearly event of the Harwinton Agricultural Society. The first written record is the Secretary's Record Book dated 1853. It is believed that the Society is some years older than that because in this book, on the first two pages, is the Constitution and, on the third page, the minutes of an Annual Meeting. This states that:
At the Annual Meeting of the Harwinton Agricultural Society held at the Town Hall March 7, 1853, the Meeting was called to order and the following appointments were made. For President Abijah Catlin; For Vice Presidents Chester N. Case, Daniel Holt and Luman Catlin; For Secretary Horatio Wetmore; For Treasurer David A. Wilson; For Executive Committee First District, Henry Birge and William Kinney; 2nd District Alonzo Barker; 3rd District Jeremiah Holt; 4th District David A. Wilson and Joseph H. Scovile; 5th District George Gridley; 6th District Oliver Pettibone and Addison Webster; 7th District George Alfred; 8th District Willis Catlin; 9th District Riley Weed; 10th District John S. Weson; 11th District Virgil Wilson; 12th District Sheldon Osborne.
Then, "at a Meeting of the Directors of the Harwinton Agricultural Society held September 12, 1853, Voted to have an Exhibition of stock, Agricultural Products and Manufactured Articles the 3rd Wednesday in October." Voted "to appoint a Commiittee of three to make the list of articles for inspection and to nominate an awarding Committee." Voted "for this Committee Abijah Caffin Esq., Oliver Pettibone and Horatio Wetmore." Meeting a djourned to the 2nd Monday evening in October.