The 2013–14 season was the 99th season of the Isthmian League, which is an English football competition featuring semi-professional and amateur clubs from London, East and South East England. The season saw all three divisions increase from 22 to 24 clubs. The regular season started on 10 August 2013 and finished on 26 April 2014 with the play-off semi-finals scheduled for the week beginning 28 April 2014 and the three finals scheduled for 3–5 May 2014. The fixture list was released during the week beginning 15 July 2013.