1999–2000 Sussex County Football League

The 1999–2000 Sussex County Football League season was the 75th in the history of Sussex County Football League a football competition in England.

Division One
Division One featured 18 clubs which competed in the division last season, along with two new clubs, promoted from Division Two:
 * Sidley United
 * Three Bridges

Division Two
Division Two featured 14 clubs which competed in the division last season, along with four new clubs.
 * Clubs relegated from Division One:
 * Broadbridge Heath
 * Hailsham Town
 * Clubs promoted from Division Three:
 * Oving Social Club, who also changed name to Oving
 * Westfield

Also, Crawley Down Village changed name to Crawley Down.

Division Three
Division Three featured twelve clubs which competed in the division last season, along with four new clubs:
 * Bosham, joined from the West Sussex League
 * Crowborough Athletic, relegated from Division Two
 * Newhaven, relegated from Division Two
 * Seaford, joined from the East Sussex League

Also, St Francis Hospital changed name St Francis.