The 2015–16 Scottish League One (referred to as the Ladbrokes League One for sponsorship reasons) was the 22nd season in the current format of 10 teams in the third-tier of Scottish football.
Promoted from Scottish League Two Relegated from Scottish Championship Teams play each other four times, twice in the first half of the season (home and away) and twice in the second half of the season (home and away), making a total of 36 games.
Cowdenbeath, the second bottom team, entered into a 4-team playoff with the 2nd-4th placed teams in 2015–16 Scottish League Two; Elgin City, Clyde, and Queen's Park.
The winners of the semi-finals, Clyde and Queen's Park, then competed against one another over two legs, with the winner replacing Cowdenbeath and being promoted to the 2016–17 Scottish League One.