Previously the Scottish Football League had a two divisional structure (Divisions One and Two) between which clubs were promoted and relegated at the end of each season. However, by the mid 1970s this organisation had become a bit stagnant and it was decided to split into a three divisional structure (Premier Division, First Division and Second Division).
This set up continued till the mid 1990s when it was decided to split into a four divisional structure with the addition of a Third Division.
In 1998 the football clubs in the Premier Division decided to split from the Scottish Football League and form the Scottish Premier League. This decision was fuelled by a desire by the top clubs in Scotland wanting to retain more of the revenue generated by the game.
Providing they meet certain criteria to do with their stadium it is still possible for clubs to be promoted from the Scottish Football League, First Division to the SPL.
Originally the SPL contained 10 clubs, but it subsequently decided to enlarge itself to a membership of 12.
Winners of the SPL title (so far):