Isthmian League 2015–16

The 2015–16 season is the 101st season of the Isthmian League, which is an English football competition featuring semi-professional and amateur clubs from London, East and South East England. Also, it is the tenth season for the current incarnations of the Division One North and Division One South.

The league constitution was announced on 15 May 2015.

After the constitution was announced, Clevedon Town of Southern League Division One South & West were demoted because their floodlights were not to the required standard. As a result, Ware were transferred to Southern League Division One Central from Isthmian League Division One North, and Redbridge were reprieved from relegation.

Premier Division
The Premier Division consists of 24 clubs: 18 clubs from the previous season, and six new clubs:
 * Brentwood Town, promoted as play-off winners in Division One North
 * Burgess Hill Town, promoted as champions of Division One South
 * Farnborough, relegated from the Conference South
 * Merstham, promoted as play-off winners in Division One South
 * Needham Market, promoted as champions of Division One North
 * Staines Town, relegated from the Conference South

Farnborough are required by the Isthmian League to pay their creditors in full before the league's 2016 AGM. If this is not fulfilled, the league will relegate the club. Therefore, if Farnborough finished top, they would not be promoted. If they finished in a play-off place, they would not be eligible to take part in the play-off competition. If they finished between 6th and 20th, they would be relegated to Step 4. If they finished between 21st and 24th, they would be relegated two steps, to Step 5.

Division One North
Division One North consists of 24 clubs: 19 clubs from the previous season, and five new clubs:
 * AFC Hornchurch, relegated from the Premier Division
 * Bury Town, relegated from the Premier Division
 * Haringey Borough, promoted as champions of the Essex Senior League
 * Phoenix Sports, promoted as champions of the Southern Counties East League
 * Witham Town, relegated from the Premier Division

Division One South
Division One South consists of 24 clubs: 20 clubs from the previous season, and four new clubs:
 * Chatham Town, transferred from Division One North
 * Dorking Wanderers, promoted from the Sussex County League
 * Molesey, promoted as champions of the Combined Counties League
 * Peacehaven & Telscombe, relegated from the Premier Division

Alan Turvey Trophy
The Alan Turvey Trophy 2015-16, formerly the Isthmian League Cup (sponsored by Robert Dyas) is the 42nd season of the Alan Turvey Trophy, the cup competition of the whole Isthmian League.