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].

Two scrap-books, compiled by 'Golyddan', containing press cuttings of the controversy in Yr Amserau, 1851, on poetic metres between 'Ieuan Gwynedd' and 'Gweirydd ap Rhys', a controversy on music between 'Ap Musicus' and Edward Stephen ('Tanymarian'), and other cuttings of literary interest; and a scrap-book compiled by Catherine Prichard ('Buddug') containing literary press cuttings, including material relating to John Robert Pryse ('Golyddan'), with a draft letter by Robert John Pryse ('Gweirydd ap Rhys').

Nearly two hundred autograph letters, 1855-1891, relating mainly to Welsh literary matters, and especially to Glamorgan, 1855-1899, to Jonathan Reynolds ('Nathan Dyfed') from contemporary Welsh poets and authors; miscellaneous poems; printed broadsides; press cuttings; etc.

Papers relating to the work of 'The Free Church Commission promoted by the National Council of Evangelical Free Churches', 1913-1914; notes entitled 'Nonconformists and Welsh Literature' and 'Adgofion am Genhadwyr'; etc.

'Casgliad Cyflawn o Lên Gwerin Cymru wedi eu cynull o Lyfrau Argraphedig Cymraeg (gan eithrio Y Mabinogion) hyd ymddangosiad Y Brython', written for the National Eisteddfod of Wales held at Liverpool, 1900.

Drafts and notes in the hand of Taliesin Williams for the volume Iolo Manuscripts, A Selection of Ancient Welsh Manuscripts, in prose and verse, from the collection made by the late Edward Williams, Iolo Morganwg,… with English translations and notes by his son, the late Taliesin Williams (Ab Iolo) of Merthyr Tydfil (Liverpool: Welsh MSS Society, 1848).
Included are manuscript drafts of the Welsh texts on pp. 3-328 passim (T4/1), drafts of the English translations on pp. 341-496 passim (T4/2), drafts for the footnotes on pp. 332-489 passim (T4/3), a draft of pp. 331-507 passim combining text and footnotes (T4/4), and notebooks containing notes and memoranda relating to the volume (T4/5-11). Also included is a bundle of draft texts, relating mostly to Welsh saints in a format similar to T4/1 but which were either omitted from the volume or intended for another book on Bonedd y Saint (T4/12).

Manuscripts, [late 12 cent.]-[early 20 cent.], formerly part of the library of the Mostyn family of Mostyn Hall, Flintshire, comprising transcripts and extracts from Giraldus Cambrensis, Geoffrey of Monmouth, Dares Phrygius, Nennius, Gildas, David Jenkins (Judge Jenkins), Sir John Wynn of Gwydir, Lydgate's 'Life of Our Lady', Leland's Itinerary, 'Chroniques de France', historical manuscripts such as Brut y Tywysiogion and Brut y Brenhinoedd, Welsh romances and the Mabinogion; collections of mainly Welsh poetry, among them the seventeenth-century volumes Llyfr Coch Nannau and Llyfr Gwyn Corsygedol, containing poems by Dafydd ap Gwilym, Guto'r Glyn, Tudur Aled, Siôn Cent and others; genealogies, pedigrees and histories; official papers relating to Caernarvonshire; catalogues of the Mostyn and Gloddaeth libraries, 1692-1842; etc.

Mae'r casgliad yn cynnwys papurau sy'n adlewyrchu gwahanol weithgareddau'r Academi yn ogystal â gweithgaredd aelodau o staff cyflogedig a swyddogion gwirfoddol y gymdeithas. Mae'n adlewyrchu y trefniant cwbl wirfoddol oedd yn bodoli rhwng 1960 a 1977, cyfraniad staff cyflogedig yn y cyfnod ers derbyn nawdd Cyngor Celfyddydau Cymru ym 1977, a'r ychwanegu a fu at weithgaredd y gymdeithas wrth greu Adran Saesneg ym 1968. Mae papurau'r Adran Gymraeg yn adlewyrchu'r cyfan o weithgaredd yr Academi hyd at sefydlu'r Adran Saesneg. O hynny ymlaen ymranna'n Adran Gymraeg, Adran Saesneg a Gweinyddiaeth Ganolog. Cynnwys ohebiaeth gyffredinol a phapurau gweinyddol cyffredinol megis cofnodion pwyllgorau, ymgyrchoedd aelodaeth, deunydd yn ymwneud â'i gwahanol gyhoeddiadau a'i amrywiol weithgareddau. Derbyniwyd 13 bocs mawr o gofysgrifau ym mis Gorffennaf 2013 a 2 focs mawr mis Hydref 2013. Nid yw'r papurau hyn wedi eu catalogio eto. = The collection consists of papers which reflect the various activities of the Academi as well as the activities of paid officials and voluntary members. They reflect the voluntary arrangement that existed between 1959 and 1977, the expansion of activities which followed the formation of the English Language Section in 1968 and the contribution made by paid staff in the period after the award of a Welsh Arts Council Grant in 1977. The papers of the Welsh Language Section reflect the whole activities of the Academi up to the formation of the English Language Section. From then on, the papers are split into those of the Central Administration, the Welsh Language Section and the English Language Section. The collection includes general correspondence, administrative papers such as committee minutes, membership details and material relating to various publications, events and activities. Thirteen large boxes of records were received July 2013 and a further 2 large boxes in October 2013. These groups remains uncatalogued.

A copy of the first issue of Trysorfa Gwybodaeth, neu Eurgrawn Cymraeg, [?3 March] 1770, each of the four sections separately paginated [1]-8 (ff. 2-5, 10-13, 18-21, 26-29), and copies of the first three sections (the news sheet is missing) from the sixth issue, [?12 May] 1770, each paginated 41-48 (ff. 6-9, 14-17, 22-25).
Also included is a sheet, March 1770, advertising the publication of the fourteenth part of Bibl Cymraeg; Gyd a Sylwiadau ac Esponiadau ar bob Pennod, ed. by Peter Williams (1770, see Libri Walliae 369-372) (f. 1).

Miscellaneous notes and papers of Iolo Morganwg, [18 cent., last ¼]-[1830s], on a variety of subjects, including (mainly Welsh) history (E8/1), religion (E8/2), Welsh and English literature, including Dr Johnson (E8/3), Bardism (E8/4) and biography and genealogy (E8/5); together with further bundles of miscellaneous notes and papers, retained in original order (E8/6-9), with subjects including politics, printing and Poems Lyric and Pastoral, 1784-[c. 1809] (E8/6), patriarchal religion, priestcraft and Lewis Morris (E8/7), poetry and monumental inscriptions (E8/8) and salmau (E8/9); and a case containing notes on Welsh manuscripts in the British Museum and at Jesus College, Oxford (E8/10).

Literary papers from various sources.

Eight notebooks of the Reverend D. Silvan Evans containing notes on Welsh grammar, language and literature.

Minutes of the Cymmrodorion council and other committees, 1873-1970, secretaries' papers, 1873-1958, 1996, librarians' papers, 1904-1939, papers relating to the Society's public activities, 1876-1988, financial papers, 1879-1954, membership papers, 1873-1933, and papers relating to its constitution, 1951-1954.

Miscellaneous notes and extracts made by Walter Davies and dealing with the language, literature, and agriculture of Wales.

Three volumes of miscellaneous notes and fragments relating to Welsh literature, history, archaeology, etc.

The legend of St. Kadok, and miscellaneous notes on Welsh grammar and literature.

Notes and articles by David Samuel on Welsh literature, including addresses entitled 'Theophilus Evans a Drych y Prif Oesoedd' and 'Some local ballad singers and ballad writers'.

Autograph letters from a large number of people to Thomas and others, mainly relating to archaeology, Welsh history, literature and ecclesiastical affairs. The correspondents include B. Beedham, William Buckland, W. Boyd Dawkins, Walter Davies ('Gwallter Mechain'), J. P. Earwaker, D. Silvan Evans, R. W. Eyton, E. A. Freeman, Margaret Gatty, Reginald Heber, Felicia Hemans, H. Longueville Jones, John Keble, Sir Theodore Martin, Sydney (Lady) Morgan, Lord Mostyn, Samuel Rogers, W. F. Skene, Sir Arthur Sullivan, John Williams ('Ab Ithel'), Morris Williams ('Nicander') and Robert Williams (Rhydycroesau); an English poem entitled 'The Sixth Centenary of Dante's Beatrice 1890' by T. Tudno Jones; and a number of 'cut-out' autographs.

Over a hundred letters, 1964-1980, from Aneirin Talfan Davies to Katharine Taylor Loesch, University of Illinois, Chicago, relating mainly to personal matters but also containing references to his work and to Welsh and English literature.

A manuscript containing a transcript of a lecture on The Influence of the Literature of Wales on that of other countries, given by Teilo at Llandilo, 16 March 1864; a note on Thomas Jones (Twm Sion Catti); material relating to the late Rev. John Evans, Llwynffortun, 1865.