Cofnodion Plaid Cymru, 1915-1999, yn cynnwys cofnodion, agenda and gohebiaeth y pwyllgor gwaith a phwyllgorau eraill, 1925-1997; gohebiaeth gyffredinol, 1925-1998, gyda nifer o aelodau a swyddogion blaenllaw y blaid; cofnodion, gohebiaeth a phapurau eraill y gwahanol bwyllgorau rhanbarthol, 1925-1997, a changhennau,1930-1992; cofnodion a dogfennaeth y Cyngor Cenedlaethol, 1967-1997; cofnodion ariannol, yn cynnwys rhai papur newydd misol y blaid Y Ddraig Goch a Welsh Nation a Chronfa Gŵyl Ddewi, 1927-1996; rhaglenni a threfniadau ar gyfer cynadleddau ac Ysgolion Haf, 1933-1998; cofnodion aelodaeth, 1930-1996; papurau y Grŵp Ymchwil, [c.1960]-1995; papurau, yn cynnwys areithiau ac effemera, yn ymwneud ag etholiadau, 1929-1999; papurau yn ymwneud ag Adran y Menywod, 1924-1996, a'r Mudiad Ieuenctid, 1964-1998; papurau yn ymwneud â refferendwm datganoli 1979,1969-1983, a refferendwm 1997, a Chynulliad Cymru,1992-1998; papurau yn ymwneud â Y Ddraig Goch, Welsh Nation a chyhoeddiadau eraill, 1932-1996; deunydd printiedig gan Blaid Cymru ac eraill yn cynnwys llyfrau, cyfnodolion a phamffledi,1913-1996; torion o'r wasg, 1924-1996; cylchlythyron, 1938-1992; papurau yn ymwneud â'r Blaid Seneddol,1980-1996; papurau unigolion ac rhai ar wahanol bynciau amrywiol, 1926-1998 = Records of Plaid Cymru, 1915-1999, including minutes, agendas and correspondence of the executive and other committees, 1925-1997; general correspondence, 1925-1998, with many prominent party members and officials; minutes, correspondence and other papers of the various regional committees, 1925-1997, and branches, 1930-1992; minutes and records of the National Council, 1967-1997; financial records, including those of the party's monthly newspaper Y Ddraig Goch and Welsh Nation and Cronfa Gwyl Dewi, 1927-1996; arrangements for and programmes of conferences and Summer Schools, 1933-1998; membership records, 1930-1996; papers of the Grŵp Ymchwil (research group), [c.1960]-1995; papers, including speeches and ephemera, relating to elections, 1929-1999; papers relating to the Adran Menywod (Women's Section), 1934-1996, and the Mudiad Ieuenctid (Youth Movement), 1964-1998; papers relating to the 1979 devolution referendum, 1969-1983, and the 1997 referendum and Welsh Assembly, 1992-1998; papers relating to Y Ddraig Goch, Welsh Nation and other publications, 1932-1996; printed matter by Plaid Cymru and others including books, periodicals and pamphlets, 1913-1996; press cuttings, 1924-1996; circulars, 1938-1992; papers relating to the Parliamentary Party, 1980-1996; papers of individuals and to various miscellaneous topics, 1926-1998.

Papurau Pwyllgor Rhanbarth Ceredigion o Blaid Cymru, yn cynnwys cofnodion,1939-1984; gohebiaeth,1944-1981; papurau'n ymwneud â gwaith a chyllid y Pwyllgor a'i ganghennau,1959-1971; papurau'r Gynhadledd Flynyddol,1976-1979; torion papur newydd,1970-1975; ymgyrchoedd, 1960-1965; adroddiadau misol Peter Hughes Griffiths, Trefnydd y pwyllgor rhanbarth,1970-1972; papurau Adran Merched Plaid Cymru,1973-1978; ffeiliau'r swyddfa ganolog, 1961-1967, a thaflenni printiedig o'r swyddfa ganolog, 1974-1985; cofnodion Cyngor Talaith Dyfed,1975-1977; gohebiaeth a phapurau ariannol cangen Aberystwyth, 1968-1979; cofnodion cangen Aberystywth,1959-1978; papurau, gohebiaeth a llenyddiaeth yn ymwneud ag etholiadau cyffredinol,1959-[1980au], ac etholiadau lleol,1963-1964. Mae grŵp ychwanegol o bapurau a dderbyniwyd yn 2000 yn dal heb eu catalogio. = Papers of the Ceredigion Area Committee of Plaid Cymru, including minutes, 1939-1984; correspondence, 1944-1981; papers relating to the work and finances of the Committee and its branches, 1959-1971; Annual Conference papers, 1976-1979; newspaper cuttings, 1970-1975; campaigns, 1960-1965; monthly reports of Peter Hughes Griffiths, the area committee organiser, 1970-1972; papers of the women's section, 1973-1978; central office files, 1961-1967, and printed leaflets from the central office, 1974-1985; minutes of the Dyfed Regional Council, 1975-1977; correspondence and financial papers of the Aberystwyth branch, 1968-1979; Aberystwyth branch minutes, 1959-1978; papers, correspondence and literature relating to general elections, 1959-[1980s], and local elections, 1963-1964. A further group of papers received in 2000 remains uncatalogued.

Mae dau grŵp o bapurau ychwanegol yn dal heb eu catalogio.