Fonds consists of minute books of the agency for the period 1949 to 2010, and a microfilm copy of the community Tweedsmuir history, microfilmed in 1984. The institute minutes include integral financial statements noting receipts and disbursements, as well as lists of officers and directors, and attendance registers. The Tweedsmuir history is composed of eight topical elements: mills, including the origin of the place name Elder's Mills, family histories and biographies, photographs, maps of original land owners, and Indigenous History; the Elder's Mill's Women's Institute, including organizational history, personal histories of membership, membership lists, etc. ; churches; schools, including Elder's Mills (School Section #15), Vaughan School (Lower Ninth) (School Section 13), Mackenzie Senior Public School, and a brief history of schools in the western half of Vaughan; roads and fences; farms, from the 7th to the 9th concession, community organizations; and services, including the Woodbridge and Vaughan Telephone Company, Woodbridger Hydro-Electric Power Commission, Toronto Grey and Bruce Railway; also included is a roll of Elder's Mills residents who served in His Majesty's Forces in World War I.