The 1928–29 season was the thirty-first in the history of the Southern League. The league consisted of Eastern and Western Divisions.[1] Kettering Town won the Eastern Division and Plymouth Argyle reserves won the Western Division. Plymouth reserves were declared Southern League champions after winning a championship play-off at Kettering 4-2.
Three clubs from the Southern League applied to join the Football League, although none were successful. Two clubs (both from the Eastern Division) left the league at the end of the season.
| Competition: | Southern Football League Eastern Division |
| Season: | 1928–29 |
| Winners: | Kettering Town |
| Promoted: | none |
| Relegated: | Gillingham II (resigned) Chatham Town (resigned) |
| Matches: | 342 |
| Total Goals: | 1365 |
| Prevseason: | 1927–28 |
| Nextseason: | 1929–30 |
A total of 19 teams contest the division, including 18 sides from previous season and one new team.
Newly elected team:
| Competition: | Southern Football League Western Division |
| Season: | 1928–29 |
| Winners: | Plymouth Argyle II (3rd title) |
| Promoted: | none |
| Relegated: | none |
| Matches: | 182 |
| Total Goals: | 799 |
| Prevseason: | 1927–28 |
| Nextseason: | 1929–30 |
A total of 14 teams contest the division, including 13 sides from previous season and one new team.
Newly elected team:
Three Southern League clubs, Aldershot Town, Thames Association and Kettering Town, applied to join the Football League. However, both League clubs were re-elected.[2]
| Club | League | Votes | |
|---|---|---|---|
| Exeter City | Football League | 42 | |
| Gillingham | Football League | 35 | |
| Argonauts | None | 6 | |
| Aldershot Town | Southern League | 5 | |
| Thames Association | Southern League | 1 | |
| Kettering Town | Southern League | 1 | |
| Llanelly | Welsh National League (South) | 0 |