"Sussex, maritime County in SE. of England, bounded N. and NE. by Surrey and Kent, SE. and S. by the English Channel, and W. and NW. by Hants; greatest length, N. and S., 27 miles; greatest breadth, E. and W., 76 miles; area, 933,269 acres, population 490,505. From the Hants border, near Petersfield, to Beachy Head, the county is traversed by the South Downs; to the N. of this range of chalk hills is the valley of the Weald, rising into the Forest Ridge on the NE., and sinking on the SE., towards the sea, into wide marshes. The rivers are not important; they are the Arun, Adur, Ouse, and Rother, all flowing S. to the English Channel. . . more"
- The East Sussex Record Office is located at The Keep at Falmer, near Brighton. It holds material for the Archdeaconry of Lewes, present-day East Sussex, and therefore generally holds historical material only for East Sussex parishes.
- An on-line catalogue for some of the collections held by the ESRO is available under the Access to Archives (A2A) project.
- The West Sussex Record Office is located in Chichester. Because it hold the records of the Diocese of Chichester, which covers the whole of Sussex, it has church records relating to both parts of Sussex.
- An on-line catalogue for some of the collections held by the WSRO is available under the Access to Archives (A2A) project
- West Sussex Past - database of 2 million records from West Sussex heritage organizations.
- The Institute of Heraldic and Genealogical Studies' Sussex Collection (PDF)
- The Sussex Record Society's Bibliography Index — catalogues and indexes publications about Sussex from over 6,500 authors who have written over 9,000 books, pamphlets and digital media and over 13,500 articles in listed journals or available online.
- The Sussex OPC Bibliography
- The Churches and Chapels of Sussex. A Bibliography
- Sussex Record Society: Books in Print - Digital Editions
- Roll of Honour - Sussex - lists of the names on over 100 Sussex war memorials
- 200 years of the Census in Sussex is a summary by the ONS of some of the main trends in Sussex revealed by the censuses (PDF, downloadable only - doesn't display in browser window) .
Sussex parishes fall almost entirely within the Diocese of Chichester
Original parish registers are held by the ESRO and WSRO, Bishops Transcipts by the WSRO:
- East Sussex Record Office: Guide to Church and Cemetery Records (Word document)
- West Sussex Record Office: Parish registers and Bishop's Transcripts
- Quaker records for Sussex, and their present location.
- IGI Batch Numbers (unofficial)
- The Sussex FHG and the Hastings and Rother FHS have contributed to the National Burial Index, available at Findmypast
- Calendar of Sussex marriage licences Archdeaconry of Lewes 1670-9, and Deanery of South Malling 1620-1732.
- West Sussex Burial Index (Sussex Record Society)
- The Sussex Family History Group has indexes covering mainly East Sussex parishes (the online databases are accessible only by society members).
- Registration Districts in Sussex for the period 1837-1974.
- An Abstract of Feet of Fines relating to the County of Sussex
- 34 Henry III - 35 Edward I (Sussex Record Society, Vol. VII)
- The WSRO has a Photographic Database with details of over 30,000 photos in its collection, 5,000 of which are available on-line.
- West Sussex Past Pictures - 5000+ images from Sussex museums and the County Library Service
Sussex books at the Internet Archive
- William Axon, Bygone Sussex London, 1897
- Wilfrid Ball, Sussex Painted, London 1906
- George F. Bosworth, Sussex (Cambridge County Geographies, 1909)
- F. G. Brabant, Rambles in Sussex, 2nd ed., London 1922
- Charles Fleet, Glimpses of our ancestors in Sussex; with sketches of Sussex characters, remarkable incidents, &c Brighton 1878 (Internet Archive)
- Handbook for Travellers in Sussex, London, 1877
- Ian Hannah, The Sussex Coast London 1912
- Augustus Hare, Sussex London, 1894
- Anthony Highmore, A ramble on the coast of Sussex (1782) Brighton 1873
- Robert Thurston Hopkins, Kipling's Sussex, London 1921
- Clare Jerrold, Picturesque Sussex Dundee 1906
- E. V. Lucas, Highways and byways in Sussex London 1904
- C. S. Ward, Surrey and Sussex, London 1897
List of Sussex Directories 1784-1975 by John H. Farrant, a comprehensive listing with details of which Sussex and national libraries hold copies.
Historical Directories of England and Wales (at the University of Leicester) has the following Sussex directories available:
- Pigot's National Commercial Directory for 1832-34 (Sussex)
- Pigot's Directory of Sussex, 1839
- Post Office Directory of Sussex 
- The Post Office Directory of Essex, Hertfordshire, Kent, Middlesex, Surrey and Sussex, 1855
- Melville and Co.'s Directory & Gazetteer of Sussex, 1858
- Melville's Directory & Gazetteer of Sussex, 1858
- Post Office Sussex Directory, 1859
- French & Son's Handbook & Directory for Worthing, 1859
- Post Office Directory of Sussex, 1866
- Post Office Directory of Sussex, 1878
- Deacon's Court Guide, Gazetteer & Blue Book of Sussex, 1881
- Kelly's Directory of Sussex, 1890
- Kelly's Directory of Kent, Surrey and Sussex, 1891
- Kelly's Directory of Sussex, 1899
- Kelly's Directory of Sussex, 1905
- Kelly's Directory of Sussex, 1911
- Kelly's Directory of Sussex, 1915
Steve Pickthall has transcribed the Sussex places in Kelly's Post Office Directory of Essex, Herts, Middlesex, Kent, Surrey and Sussex, 1867. See the parish pages for links to these transcriptions.
The Sussex OPC scheme is currently transcribing 22 Sussex directories
- Sussex Family History Group Members' Interests (a more comprehensive list is available to society members)
- Sussex Lookup Requests (RootsChat)
- The SUSSEX-PLUS mailing list - includes Sussex, Kent, Surrey, Hampshire and the Isle Of Wight, though main focus is on Sussex now that the other counties have their own lists
- Sussex Forum on RootsChat
- Sussex Forum on British-Genealogy
- The Sussex Online Parish Clerks scheme researches all the available historical data they can find on a parish, and transcribes records.
- List of topographical articles in the Sussex volumes of the Victoria County History
- Sussex Archaeological Society
Victoria County History
- The Victoria history of the county of Sussex. (Vol 2), London 1905 (covers Ecclesiatical History, Religious Houses, Social and Ecenomic History, Industries, Agriculture, Schools, Sport)
- Charles Thomas-Stanford, Sussex in the great Civil War and the interregnum, 1642-1660 London 1910
- Report of the Poor Law Commissioners on the agricultural disturbances of 1830: East Sussex
- Volume 1 Natural History
- Volume 2 Religious Houses
- Volume 3 City of Chichester
- Volume 4 Rape of Chichester
- Volume 5, Part 1 Arundel Rape (SW part)
- Volume 6, Part 1 Bramber Rape (S part)
- Volume 6, Part 2 Bramber Rape (NW part)
- Volume 6, Part 3 Bramber Rape (NE part)
- Volume 7 Rape of Lewes
- List of topographical articles in the Sussex volumes of the Victoria County History
- Rev. W. D. Parish, A dictionary of the Sussex dialect and collection of provincialisms in use in the county of Sussex Lewes, 1875. Transcribed version at Sussex History.
- E. V. Lucas "The Sussex Dialect" (Highways and Byways in Sussex, Macmillan 1904, Chapter XLI)
- Sven Rubin, The Phonology of the Middle English Dialect of Sussex, Lund 1951
- Jonathan Roper, Sussex glossarists and their illustrative quotations, Sussex Archaeological Collections, 145 (2007), pp 181-94.
- Richard Coates, The Traditional Dialect of Sussex: A Historical Guide, Description, Selected Texts, Bibliography and Discography, Pomegranate Press, 2010
- Sussex dialect (Wikipedia)
- Sound recordings:
- Example of Sussex dialect at the British Library Sound Archive.
- The Sussex Dialect of R.W. White from Battle, recorded by the British Drama League in the 1920s (YouTube).
- Old Sussex Mapped: Two centuries of Sussex County Maps - 10 historical maps of Sussex, starting with John Speed's map of 1610, including extensive historical commentary.
- Genmaps has many historical maps of Sussex as a whole and of individual towns (archived copy at the Wayback Machine)
- Old-maps has digitised the 19th Century 6" Ordnance Survey Maps.
- The Weald of Sussex - Maps
- The Royal Sussex Regiment (originally 35th Regiment of Foot)
- The Sussex Yeomanry (1908-1918)
- Redoubt Fortress Museum, the Military Museum of Sussex (Heritage Eastbourne)
- Historical Gazetter of Sussex Place Names from the maps on the Two centuries of Sussex County Maps site.
- R. G. Roberts The Place-names of Sussex, Cambridge University Press 1914. Note, however, that this has been superseded by
- The Place-names of Sussex, 2 vols, Cambridge University Press 1929-30 (reprinted 1986), which is more comprehensive.
- Richard Coates, A Classified Bibliography on Sussex Place-Names, 1586-1987, Younsmere Press, Brighton 1987.
- West Sussex Protestation Returns 1641-2 (Sussex Record Society)
- Surrey Institutional Records 1788-1939 (Findmypast). Includes:
- Cobham, Reed’s School Annual Reports 1818-1901
- Mayford Industrial School Admissions 1895-1907
- Redhill, Royal Philanthropic School Admission Registers 1788-1906
- The Three Earliest Subsidies For the County of Sussex 1296, 1327, 1332 (Sussex Record Society, Vol. X)
- The Lay Subsidy Rolls for the County of Sussex 1524-1525 (Sussex Record Society)