Diaries etc, 1903-1930; sermons; addresses and articles, 1916-1948; correspondence, notes and articles relating to penal reform, 1907-1917, Ireland, 1920-1924, education, 1925-1931, reparations, 1926-1931, Tom Nefyn Williams, 1926-1931, and the Fellowship of Reconciliation, 1916-1947; poetry, 1900-1947; genealogical and miscellaneous notes and family papers, 1884-1926; articles and addresses by various authors, 1903-1949; letters to and from George M. Ll. Davies, other members of the family and others, 1826-1964.

Press cuttings relating to Wales and Welsh culture, such as religion, politics, literature, music, education, St. David's Day celebrations and the Eisteddfod Genedlaethol, individuals, and the National Library of Wales [1895]-[1939].

Papers of D. A. Thomas, Viscount Rhondda, including letters to D. A. Thomas on political matters such as working conditions in the mining industry, education, church disestablishment, and the temperance movement, 1891-1910 (mainly 1891-1895); drafts and copies of letters from D. A. Thomas on similar subjects, 1891-1895; miscellaneous letters, 1893-1895; subject files, 1874-1917, on the coal industry, including the Cambrian Navigation Collieries, the Mining Association of Great Britain, the South Wales Liberal Federation, temperance and disestablishment; scrapbooks of press cuttings, 1894-1927, relating to Cymru Fydd, D.A Thomas, Merthyr politics and Keir Hardie, the Lusitania, and Lady Rhondda; miscellaneous items, 1897-1934, including genealogical material and congratulatory addresses to D.A.T.; circulars and memoranda.

The collection comprises John Owen's diaries, 1889-1926; notebooks containing press cuttings, accounts, extracts from the Bible and historical notes; and an address book (box 1); the memoirs of John Owen entitled 'College Friends', letters, 1872-1894, including many letters concerning the tithe rent charge, papers on the 1889 Welsh Intermediate Education Bill (box 2); a catalogue of the books in the library of Bishop John Owen, 1908, speeches, draft speeches and sermons, letters and papers relating to the disestablishment and disendowment of the church in Wales, papers concerning educational matters, 1891-1895 (box 3); letters, 1893-1897, many on religious matters, including issues of church reform, some of family interest, some congratulating John Owen as Bishop of St Davids in 1897 (box 4); an incomplete manuscript, the final printers' copy and the typescript text of 'The Early Life of Bishop Owen' (box 5); letters, 1898-1905, some relating to sermons and prayers following the death of Gladstone, the 1902 Education Bill, church defence, the fire at the Bishop's Palace at Abergwili in 1903, the new Bishop of Llandaff in 1905, and matters of diocesan interest, and there are also papers, 1904-1905, concerning education, Lloyd George and the Western Mail (box 6); letters, 1897-1914, some relating to the proceedings of the Welsh Church Commission, diocesan matters, church defence etc. (box 7); correspondence and papers, 1914-1917, many relating to the disestablishment and disendowment of the Church in Wales, the Welsh Church Act, 1914, and related matters (box 8); letters, 1906-1915, some relating to the role of the church in politics, education, church defence, the Welsh Church Bill etc. (box 9); correspondence and printed material, 1914-1919, concerning disestablishment, the Welsh Church Act, the Postponement Bill and the war, the tithe and disendowment (box 10); letters and papers, 1910-1926, concerning the tithe and the Welsh Church Bill, the Welsh Church Act, the Church Commissioners, matters relating to the diocese of St Davids (box 11); bundles of letters, 1922-1926, relating to church and diocesan matters, disestablishment and finance (box 12); correspondence and papers, 1914-1926, relating to disendowment, the government of the Church in Wales, the constitutions of the Governing Body and the Representative Body of the Church in Wales, drafts, notes and correspondence concerning 'The Later Life of Bishop Owen' (box 13); papers, 1907-1918, concerning Bishop Owen's life and work, including the typescript draft of 'The Early Life of Bishop Owen' (box 14); typescript drafts of 'The early Life of Bishop Owen' (box 15); manuscript texts of 'The Later Life of Bishop Owen', and miscellaneous source materials relating to Bishop Owen's life and work (box 16); papers concerning church matters, 1889-1925, including material relating to the Ecclesiastical Commissioners, the Representative Body of the Church in Wales, the 'Diocesan Board of Finance', the 'Million Pound Fund' appeal, commutation capital, the St Davids Board of Finance etc., together with the correspondence of Miss Eluned Owen, 1954-1965 (box 17); papers relating to voluntary and parochial contributions, 1905-1908, together with an extensive collection of press cuttings (box 18).
Additional papers (boxes 19-21) comprising the letters of Bishop John Owen, his wife Amelia Owen and their family, together with the recollections of their daughter, Gwenonwy Davies, and of her husband the Very Reverend J. T. Davies, Dean of Bangor, were received in August 2017.

Papers, 1889-1988, of Ben G. Jones, including academic notes, 1932-1935; personal letters, 1942-1968; political papers, 1935-1985; correspondence relating to politics in Merionethshire, 1963-1967; press cuttings, 1958-1963, printed material relating to the four main political parties in Wales, 1949-1966; papers relating to the Honourable Society of Cymmrodorion, 1939-1988; minute book, 1889-1909, of the London Welsh Mutual Improvement Societies' Union; papers deriving from the compilation and publication of the Dictionary of Welsh Biography, 1953-1986; papers relating to his public life, 1968-1984, including the Kilbrandon Commission, 1936-1969, the BBC, 1968-1978, UCW Aberystwyth, 1968-1985, and the Agricultural Land Tribunal, 1980-1984; minute book, 1889-1909, of the London Welsh Mutual Improvement Societies' Union; and papers relating to the status of the Welsh language and to teaching and broadcasting through the medium of Welsh, 1965-1987.

One of two volumes comprising a group of two hundred and twenty-four autograph letters and copies and fragments of letters covering the period 1823-1917 and addressed chiefly to 'Nefydd'. -- There are references to British Schools at Holywell, Abertillery, Llanelly, and Pantyphilip; a proposal to transfer Ellis Evans's Baptist manuscripts to Llangollen Baptist College; a proposal to publish the works of 'P. A. Môn'; Baptist activities in America and Australia; the Baptist cause at Caerleon and in Monmouthshire generally; a proposal to safeguard 'Carnhuanawc's library; and the Vronissa Lead Mine, Ruthin. David Morris, writing from Tasmania, states that on the night of his wife's funeral he was given ten shillings by 'Shoni Sgubor Fawr'. -- The writers include: D. Oliver, Merthyr; J. G. Owen, Brynsaithmarchog; Wm. Palmer, Liverpool; Edw[ard] Parry, Chester; D. Phillips, Caerleon; Philip D. Phillips, Utica, New York; Ben Price; Thos. Price, Aberdare; John Prichard, Llangollen; David Rees, Llanelly; Edward Roberts ('Iorwerth Glan Aled'), Denbigh and Rhumney; Edward Roberts, Haverfordwest; [John Roberts, Tredegar]; W. Roberts, Tredegar; 'Nefydd' to [Jane Williams, Aberpergwm], John Michael, Abergavenny, Robert Ellis ('Cynddelw'), etc.; Lewis Thomas, Port Adelaide, South Australia; J. R. Loomis, University of Lewisburg, and P. L. Davies, Camden, Pennsylvania, with copy replies; Jas. Rowe, Risca and Fishguard; Robert Saunders, British and Foreign School Society, London; James Spencer, Llanelly; D. Rhys Stephen, Swansea; 'Teilo', Llandilo; Evan Thomas, Maesaleg; George Thomas, Pontypool; [John Thomas] ('Eifionydd'); John Thomas, ('Pencerdd Gwalia'); John Thomas, Llanelly; J. Thomas, Liverpool; W. Thomas, Newport; T. E. Watkins ('Eiddil Ifor') to the editor of The Monmouthshire Merlin; B. Williams, Merthyr; Edward Williams, Aberystwyth; H. Williams, Bettws; Hugh Williams, Pentrebach, Pontypridd, to Caleb Lewis and 'Ap Nefydd'; J. Williams, Rhos; John Williams, Newtown; Lewis Williams, [Llanddulas]; J. Mostyn Williams, Liverpool; J. O. Williams ('Pedrog') to Evans; M[aria] J[ane] Williams, Ynislas [and Aberpergwm]; Owen Williams, Holywell; William Williams ('Creuddynfab'); etc.

A group of forty-two autograph letters, 1839-72, addressed chiefly to 'Nefydd', and similar in character to those earlier groups of 'Nefydd' letters which have been previously described (NLW MSS 7163-6, 7176-7). -- The writers include: 'Ceinwalch', Llanover; J. C. Davies, Holywell; Christmas Evans; John Evans, Llansantffraid Glan Conwy; Dd. Griffiths, Cwmavon; Thomas Griffiths, Cae Newydd; Anne Hiley, Varteg; J. Hiley, Llanwenarth; H. E. P. Hughes, Neath; 'Ieuan ap Gruffydd', London; Daniel Jones, Risca and Llanelly; Jane Rowland Jones, Liverpool, and 'Elin'; Jane Jones, Llanelly, Cowbridge, and Cross Inn; J. Jones, Zion, Merthyr; Josiah Thomas Jones Carma, and Aberdare; Theophilus Jones, Philadelphia; Wm. B. Jones, Emporia, Kansas; L. W. Lewis ('Llew Llwyfo'); [John Owen] 'Owain Alaw', Chester; John Prichard, Llandudno, to Ellis Evans; A. Roberts [sister of 'Nefydd']; 'Nefydd' to his wife and to Daniel Jones; D. Rhys Stephen; Eliza Hannah Thomas, Cross Inn, to Eliza Jane [Roberts]; Thos. Thomas, Pontypool; [David Williams] 'Alaw Goch' Aberdare; J. Williams, Newtown; J. Williams, Rhos, to Ellis Evans; Owen Williams, Holywell; and [William Williams] 'Creuddynfab'.

Records of the Association of Welsh Local Authorities, 1928-1976, including minutes of annual meetings, 1952-1973; minutes of council meetings, 1952-1973; cash books, 1958-1973; administration papers, 1953-1976, papers relating to the withdrawal of railway services in Wales, 1962-1970; and subject files, 1952-1974, relating the interests and activities of the Association, such as water resources, transport, education, and the Welsh economy.

Addresses by Philip Thomas entitled 'Beth fedr yr Ysgol Sabbothol ddysgu oddiwrth yr Ysgol ddyddiol?' and 'Y dull goreu o gyfranu addysg i blant'.

A ledger, 1877-1888, kept by Edwin Jones, showing detail the expenses incurred by boarders at Brynarvor School, Towyn, a printed prospectus of Brynarvor School, and a time table of evening classes held, 1881-1882.

A notebook containing three addresses in Welsh by Philip Thomas entitled 'Braslun o Hanes Caniadaeth Grefyddol yn Nghymru' (f. 1-9 verso), 'Y dull goreu o gyfranu addysg i blant' (ff. 10-14 verso), and 'Holi' (ff. 15-21), delivered to Cymanfa Gerddorol Methodistiaid Dosparth Castellnedd, Good Friday, 1891, Cyfarfod Daufisol Ysgolion Sabbothol Methodistiaid Castellnedd at Fforest, Aberdulais, January 1891, and Cyfarfod Daufisol Castellnedd at Bethlehem Green, 7 May 1893, respectively; and 'The Laws of Questioning', notes taken from a work by Dr Vincent (ff. 22-24 verso).

Press cuttings, typescript and manuscript notes and accounts, correspondence and printed material, 1894-1917, relating mainly to Aberystwyth County School and its headmaster, David Samuel, and to other Welsh county schools and education in Wales.
The material relating to Aberystwyth County School includes details of a court case, July 1903, involving David Samuel and Mary Isabel Guilbert, a pupil at the school. The remaining material includes typescript and manuscript notes and accounts [by C. M. Williams, Carmarthen], 1894-1914, relating to other county schools in Wales; correspondence, 1903-1917, including two telegrams, dated 30 July 1903, to C. M. Williams, a letter, 1903, to David Samuel from R. H. Guilbert and two letters, 1904, to C. M. Williams from J. Austin Jenkins, Cardiff; and a printed copy, dated May 1902, of a Board of Education report on education and school administration in Wales.

Papurau Cynog Dafis, yn cynnwys gohebiaeth gyffredinol,1964-1973, ffeiliau yn ymwneud ag addysg, 1961-1982, ffeiliau yn ymwneud â chynghrair Plaid Cymru/Y Blaid Werdd yng Ngheredigion, 1991-1997, papurau, 1996-1997, yn ymwneud ag etholiad cyffredinol 1997, areithiau, ymgyrch llywyddiaeth Plaid Cymru ac etholiad Cynulliad Cenedlaethol Cymru 2007 = Papers of Cynog Dafis, including general correspondence, 1964-1973, files relating to education, 1961-1982, files relating to the Plaid Cymru / Green Party alliance in Ceredigion, 1991-1997, papers relating to the 1997 general election, 1996-1997, speeches, campaign for the role of President of Plaid Cymru and the National Assembly for Wales election 2007.

Derbyniwyd papurau ychwanegol sydd dal heb eu catalogio = Addition papers received remain uncatalogued.

Papurau T. Ll. Stephens, 1928-1959, yn cynnwys yn bennaf cyfansoddiadau llenyddol, a hefyd papurau'n ymwneud ag addysg, addysg ddwyieithog a Dewi Emrys, ynghyd a grŵp bach o lythyrau a phapurau eraill Dewi Emrys,1940-1953 = Papers of T. Ll. Stephens, 1928-1959, mainly comprising his literary compositions, and also including papers relating to education, bilingual education and Dewi Emrys, together with a small group of letters and other papers, 1940-1953, of Dewi Emrys.

Papurau'n ymwneud â Rhieni dros Addysg Gymraeg, 1963-1988, yn cynnwys copïau o gofnodion, 1963-1988, y Cyfarfodydd Cyffredinol Blynyddol a chofnodion y Pwyllgor Gwaith; adroddiadau blynyddol, 1984-1988; copi o gyfansoddiad y grŵp a luniwyd yn 1983; gwahanol adroddiadau a baratowyd gan y grŵp, 1983-1988; ac adroddiadau a baratowyd gan bwyllgorau sir y mudiad, 1981-1987. = Papers relating to Rhieni dros Addysg Gymraeg1963-1988, including copies of minutes, 1963-1988, of the AGMs and the executive committee minutes; annual reports, 1984-1988; a copy of the group's constitution prepared in 1983; various reports prepared by the group, 1983-1988; and reports prepared by the movement's county committees, 1981-1987.

Papurau ychwanegol gan gynnwys papurau'r Gynhadledd Flynyddol, 1983-1987; cyfrol yn cynnwys cyfansoddiad 'Undeb Rhieni Ysgolion Cymraeg', a chofnodion cyfarfodydd, 1963-1982; a papurau Taflen 'Holi ac Ateb'. Nid yw'r papurau hyn wedi eu catalogio eto.