The Premier Division is the top division of the Isthmian League. It was at the sixth tier of the English football league system from 1985-2004 but is now at the seventh tier. For sponsorship reasons, it is often referred to as the Ryman League Premier Division.

The division is run in parallel with the Premier Divisions of the Northern Premier League and the Southern League. The winners of each league are promoted to either the Conference North or Conference South divisions, while the runners up enter a play-off, also offering the possibility of promotion. Clubs relegated from the Premier Division will drop to the Isthmian League First Division or potentially into the Southern League Division One East depending on their location.

Prior to the 2004-2005 season, the division winners were promoted to the Football Conference (along with the Northern Premier League and Southern League winners), while the lowest placed teams were in recent seasons relegated to either the Isthmian League Division One North or the Isthmian League Division One South .

Current Clubs

Future Clubs

• AFC Wimbledon (assured of promotion to Premier Division for 2005-06 season as First Division champions)
• Walton & Hersham (assured of promotion to Premier Division for 2005-06 season as First Division runnerup)