Isthmian League Division One South

The Isthmian League Division One South is a division of the Isthmian League. It is at the eighth tier of football in England. It runs in parallel to the Isthmian League Division One North. The champions and play-off winners are promoted to the Isthmian League Premier Division. It is sponsored by Ryman, and therefore officially known as the Ryman League Division One South.

Member clubs 2009–10
1Transferred from Division One North due to location 2Promoted 3Relegated

Champions
For champions of predecessor leagues see Isthmian League First Division, Isthmian League Second Division and Isthmian League Third Division.