Division One North
Division One South
|Number of teams||66
22 (Premier Division)
22 (Division One North)
22 (Division One South)
|Feeder to||Conference South|
|Levels on pyramid||7 and 8|
|Domestic cup(s)||FA Cup
Isthmian League Cup
|Current champions||Dover Athletic (Premier Division)
Aveley (Division One North)
Kingstonian (Division One South)
|2009–10 Isthmian League|
Before the Isthmian League was formed, there were no leagues in which amateur clubs could compete, only cups. Therefore a meeting took place between representatives of Casuals, Civil Service, Clapton, Ealing Association, Ilford and London Caledonians to discuss the creation of a strong amateur league. All the clubs supported the idea and the Isthmian League was born on 8 March 1905. Membership to the league was through invitation only. The league was strongly dedicated to amateurism; the champions did not even receive a trophy or medals; the league motto was honour sufficit. Teams less able to compete financially thus gravitated to it rather than the Southern League, while those with ambition and money would move in the opposite direction. Although the league established itself as one of the strongest amateur leagues in the country, routinely providing the winners of the FA Amateur Cup, it was still seen as being at a lower level than the Southern League and Northern Premier League which were the top regional semi-professional leagues. By 1922 the league had fourteen clubs and over the next five decades, only a few new members were admitted, mainly to fill vacancies left by clubs leaving the league. Most new Isthmian League members joined from the Athenian League, which was similarly dedicated to amateurism. The Isthmian League was most likely named after the ancient Isthmian Games, with the later Athenian League, Corinthian League and Delphian League all adding a Classical flavour to amateur football competition.
The league began to admit professionalism in the 1970s. A second division of sixteen clubs was formed in 1973 and a third division followed in 1977. The league refused to participate in the formation of the Alliance Premier League in 1979. Two Isthmian clubs, Enfield and Dagenham, defected to the APL in 1981 but it was not until 1985 that the Isthmian League champions were given a promotion place to the newly renamed Football Conference. The reward of promotion into the Conference means that, since 1985, no team has retained the title (as had happened on 22 occasions previously). The Athenian League disbanded in 1984 when the Isthmian League Second Division split into North and South divisions. These were restructured again to Second and Third divisions in 1991.
In 2002, the league was restructured again, with the First and Second Divisions merging to become First (North) and First (South), and the Third Division being renamed as the Second. In addition, the Isthmian's three feeder leagues—the Combined Counties League, Essex Senior League and Spartan South Midlands League—ran in parallel with the Isthmian Second, and were able to feed directly into the regional First Divisions.
In 2004, The Football Association pushed through a major restructuring of the non-league National League System, creating new regional divisions of the Football Conference. The Isthmian League was reduced back down to three divisions, and its boundaries were changed to remove the overlap with the Southern League.
In 2006, further reorganisation saw a reversion to two regional First Divisions (North and South) and the disbandment of the Second Division. This current plan calls for clubs based on the edges of the Isthmian League's territory to transfer to and from the Southern League as necessary to maintain numerical balance between the leagues. One team, Clapton, had been ever-present in the Isthmian League since its foundation, but they moved to the Essex Senior League for the 2006–07 season.
The Isthmian League was the first league to have sponsorship, having been selected by Rothmans, who sponsored the club from 1974 to 1977. The company offered prize money for position in the league; this money was reduced for bookings. Thus the money encouraged more goals and fair play. The sponsors after Rothmans to the present day are: Michael Lawrie (1977–78), Berger (1978–82), Servowarm (1982–85), Vauxhall-Opel (1985–90), Vauxhall (1990–91), Diadora (1991–95), Icis (1995–97) and Ryman (1997–present).
The Isthmian League Cup has run since 1975 and involves all Isthmian League teams.
Since 2007, the Isthmian League has run a youth league called the Isthmian Youth League. This league is not restricted to members of the Isthmian League.
|1914–19||Postponed due to World War I|
|1923–24||St Albans City|
|1926–27||St Albans City|
|1927–28||St Albans City|
|1939–45||Postponed due to World War II|
|1957–58||Tooting & Mitcham United|
|1959–60||Tooting & Mitcham United|
For the 1973–74 season, Division One was added.
|Season||Premier Division||Division One|
|1974–75||Wycombe Wanderers||Staines Town|
For the 1977–78 season, Division Two was added.
|Season||Premier Division||Division One||Division Two|
|1977–78||Enfield||Dulwich Hamlet||Epsom & Ewell|
|1978–79||Barking||Harrow Borough||Farnborough Town|
|1980–81||Slough Town||Bishop's Stortford||Feltham|
|1981–82||Leytonstone & Ilford||Wokingham Town||Worthing|
|1983–84||Harrow Borough||Windsor & Eton||Basildon United|
For the 1984–85 season, Division Two was reorganised into North and South regions.
|Season||Premier Division||Division One||Division Two North||Division Two South|
|1984–85||Sutton United||Farnborough Town||Leyton Wingate||Grays Athletic|
|1985–86||Sutton United||St Albans City||Stevenage Borough||Southwick|
|1986–87||Wycombe Wanderers||Leytonstone/Ilford||Chesham United||Woking|
|1987–88||Yeovil Town||Marlow||Wivenhoe Town||Chalfont St Peter|
|1988–89||Leytonstone/Ilford||Staines Town||Harlow Town||Dorking|
|1989–90||Sutton United||Wivenhoe Town||Heybridge Swifts||Yeading|
|1990–91||Redbridge Forest||Chesham United||Stevenage Borough||Abingdon Town|
For the 1991–92 season, Division Two North and South were merged and Division Three was added.
|Season||Premier Division||Division One||Division Two||Division Three|
|1991–92||Woking||Stevenage Borough||Purfleet||Edgware Town|
|1992–93||Chesham United||Hitchin Town||Worthing||Aldershot Town|
|1993–94||Stevenage Borough||Bishop's Stortford||Newbury Town||Bracknell Town|
|1994–95||Enfield||Boreham Wood||Thame United||Collier Row|
|1995–96||Hayes||Oxford City||Canvey Island||Horsham|
|1996–97||Yeovil Town||Chesham United||Collier Row & Romford||Wealdstone|
|1997–98||Kingstonian||Aldershot Town||Canvey Island||Hemel Hempstead Town|
|1998–99||Sutton United||Canvey Island||Bedford Town||Ford United|
|1999–00||Dagenham & Redbridge||Croydon||Hemel Hempstead Town||East Thurrock United|
|2000–01||Farnborough Town||Boreham Wood||Tooting & Mitcham United||Arlesey Town|
|2001–02||Gravesend & Northfleet||Ford United||Lewes||Croydon Athletic|
For the 2002–03 season, Division One was reorganised into North and South regions and Division Three was disbanded.
|Season||Premier Division||Division One North||Division One South||Division Two|
|2002–03||Aldershot Town||Northwood||Carshalton Athletic||Cheshunt|
|2003–04||Canvey Island||Yeading||Lewes||Leighton Town|
For the 2004–05 season Division One North and South were merged.
|Season||Premier Division||Division One||Division Two|
For the 2006–07 season, Division One was reorganised into North and South regions and Division Two was disbanded.
|Season||Premier Division||Division One North||Division One South|
|2006–07||Hampton & Richmond Borough||AFC Hornchurch||Maidstone United|
|2007–08||Chelmsford City||Dartford||Dover Athletic|
AFC Hornchurch | Ashford Town (Middx) | Aveley | Billericay Town | Bognor Regis Town | Boreham Wood | Canvey Island | Carshalton Athletic | Cray Wanderers | Dartford | Harrow Borough | Hastings United | Hendon | Horsham | Kingstonian | Maidstone United | Margate | Sutton United | Tonbridge Angels | Tooting & Mitcham United | Waltham Abbey | Wealdstone
Brentwood Town | Cheshunt | Concord Rangers | East Thurrock United | Enfield Town | Great Wakering Rovers | Harlow Town | Heybridge Swifts | Ilford | Leyton | Lowestoft Town | Maldon Town | Northwood | Potters Bar Town | Redbridge | Romford | Thamesmead Town | Tilbury | VCD Athletic | Waltham Forest | Ware | Wingate & Finchley
Ashford Town (Kent) | Burgess Hill Town | Chatham Town | Chipstead | Corinthian-Casuals | Croydon Athletic | Dulwich Hamlet | Eastbourne Town | Fleet Town | Folkestone Invicta | Godalming Town | Horsham YMCA | Leatherhead | Merstham | Metropolitan Police | Ramsgate | Sittingbourne | Walton & Hersham | Walton Casuals | Whitstable Town | Whyteleafe | Worthing