Research and personal papers of Dafydd Jenkins, comprising correspondence, drafts and other papers relating to his articles and books, [1937]-1997; correspondence, 1935-1989, on subjects including legal and academic matters, 1972-1991, evening classes given by DJ on agricultural subjects, 1944-1957, the New Welsh Language Act Campaign, 1983-1987, broadcasting, 1950-1963, and publishing, 1942-1989; papers concerning the Welsh language, 1972-1992; papers, 1938-1939, relating to the Welsh Language Petition, including circulars and newsletters; papers relating to British Legal History Conferences, 1971-1995, and International Congresses of Celtic Studies, 1967-1975; correspondence, minutes and other papers relating to organisations including Plaid Cymru, the National Eisteddfod, Undeb Cymru Fydd, the Sociological Group of the Church in Wales and the Milk and Dairies Tribunal for Wales, 1947-1979; ecumenical papers relating to Siloh Calvinist Methodist Chapel, Aberystwyth, 1958-1970; miscellaneous papers relating to various associations, societies, and organizations, 1969-1996; printed material relating to Plaid Cymru and Denmark, 1938-1970.