The 2004–05 season was the 102nd in the history of the Southern League, which is an English football competition featuring semi-professional and amateur clubs from the East Midlands, West Midlands, East, South East and South West England.
Also, it was the first season after the creation of the Conference North and South, one step above the Southern League. Therefore, it was the inaugural season for the league at the seventh and eighth tiers in the English league system.
After the creation of the Conference North and South placed above the Southern League, most of the previous season clubs were transferred to the newly created divisions.
Histon won the Premier Division and get a second promotion in a row along with play-off winners Hednesford Town. Hemel Hempstead, Dunstable, Stamford and Solihull Moors were relegated and returned to Division One.
The Premier Division featured only six clubs from the previous season and 16 new clubs:
After the creation of the Conference North and South one step above the Southern League, most of the Premier Division clubs were transferred to the newly created divisions. Consequently, most of the Eastern Division clubs took up the empty spots in higher divisions.
Fisher Athletic won the division and were promoted along with runners-up East Thurrock United and play-off winners Maldon Town, who get the second promotion in a row. Erith & Belvedere and Tilbury finished bottom of the league and were relegated.
In the first season as an eighth tier league, the Eastern Division featured five clubs from the previous season and 17 new clubs:
After the creation of the Conference North and South one step above the Southern League, most of the Premier Division clubs were transferred to the newly created divisions. Consequently, most of the Western Division clubs took up the empty spots in higher divisions.
Mangotsfield United won the division and were promoted to the Premier Division along with runners-up Yate Town and play-off winners Evesham United. Oxford City and Egham Town finished bottom of the table and were relegated.
In the first season as an eighth tier league, the Western Division featured eleven clubs from the previous season and eleven new clubs: