The Scottish Football League (SFL) was a league featuring professional and semi-professional football clubs mostly from Scotland. From its foundation in 1890 until the breakaway Scottish Premier League (SPL) was formed in 1998, the SFL represented the top level of football in Scotland.

After 1998, the SFL represented levels 2 to 4 of the Scottish football league system. In June 2013, the SFL merged with the SPL to form the Scottish Professional Football League.

The SFL was associated with a title sponsor from the 1985–86 season. As this sponsor changed over the years the league was known in turn as the Fine Fare League, B&Q League, Bell's Scottish Football League and finally as the Irn-Bru Scottish Football League.

The SFL also organised two knock-out cup competitions, the Scottish League Cup and the Scottish Challenge Cup.

Organised football in Scotland began in 1873 with the formation of the Scottish Football Association (SFA). During the next 15 years or so, clubs would play friendly matches, Scottish Cup ties and local cup (e.g. Glasgow Cup or East of Scotland Shield) ties. 

The Football League, initially containing clubs from the North West and Midlands of England, was formed in 1888. This had been done in response to the professionalisation of football in England in 1885, with the regular diet of league fixtures replacing the haphazard arrangement of friendlies. Many Scottish players, known as the Scotch Professors, moved to the English league clubs to receive the relatively high salaries on offer.  This prompted Scottish clubs into thinking about forming their own league.

In March 1890, the secretary of Renton wrote to thirteen other clubs inviting them to discuss the organisation of a league. All of the clubs accepted the invitation, except Queen's Park and Clyde.

Amateur club Queen's Park, who were the oldest organised club in Scotland and had played a key role in the development of football, were opposed to the league because it would lead to professionalism and eliminate many of the smaller clubs. These concerns were to prove well-founded, as six of the founder members would leave the league before 1900.

The Scottish Football League (SFL) was inaugurated on 30 April 1890. The first season of competition, 1890–91, commenced with 11 clubs because St Bernard's were not elected. The eleven original clubs in membership were Abercorn, Cambuslang, Celtic, Cowlairs, Dumbarton, Heart of Midlothian, Rangers, Renton, St Mirren, Third Lanark Rifle Volunteers and Vale of Leven.

Renton were expelled after five games of the 1890–91 season for playing against St Bernard's, who had been found guilty of concealed professionalism. Renton raised an action against the SFA in the Court of Session and won, which meant that their SFA and SFL memberships were restored.

In the 1890–91 season, Rangers and Dumbarton were level at the top of the league on 29 points. The teams drew 2–2 in a play-off match, but no further thought had been given to separating teams by another method and the championship was shared.

Goal average was introduced for the 1921–22 season and replaced by goal difference for the 1971–72 season.

The league proved to be highly successful, and in 1893 a Second Division was formed by the inclusion of a number of clubs previously in the Scottish Football Alliance. Promotion was initially based on a ballot of clubs; automatic promotion was not introduced until 1922.

The onset of the First World War saw the Second Division, but not the First Division, being suspended, not restarting again until 1921 when the Central Football League was absorbed as a new division with automatic promotion.

In 1923, the League decided to introduce a Third Division. The Western League was used as its backbone but the new set-up lasted only three years before it collapsed under heavy financial losses.

From 1926 until 1946, the League reverted to two divisions with many of the third tier clubs joining the Scottish Football Alliance. Post Second World War reforms saw the League resume with three divisions, renamed 'A', 'B' and 'C' with the last section also including reserve sides.

In 1949, the 'C' Division was expanded to two sections – North-West and South-East. The withdrawal of the reserves from 'C' Division in 1955 saw a return to two divisions with the 5 first teams in Division C being given automatic promotion. There were then 18 clubs in Division A and 19 in Division B.

In 1956 the divisions were renamed Division 1 and Division 2. Clydebank were elected to Division Two as the 20th club in 1966, but following the demise of Third Lanark in 1967, the Second Division kept operating with just 19 clubs; the situation would not be corrected until the next change of format, which happened in 1975.

This change of structure split the league into three divisions, Premier, First, and Second Divisions. This permitted more frequent fixtures between the top clubs; the expectation was that meant greater revenue for them, and it was hoped it would stimulate greater interest, at a time when attendance at league matches had dropped alarmingly. A new club entered the league, Meadowbank Thistle (which would eventually become Livingston). This three-divisional structure of 38 clubs continued until 1994.

After a couple of decades, the league again reorganised, with four divisions of 10 clubs, as Inverness Caledonian Thistle and Ross County were elected to round out the league. At the same time, the SFL adopted the system of three points for a win.

In 1998 the Premier Division clubs split from the league to form the Scottish Premier League (SPL). The remaining leagues, of ten clubs each, kept their names and the Premier Division was not reconstituted, leaving First, Second and Third Divisions.

Part of the agreement was that the SPL would expand to 12 clubs in 2000. The SFL then took in two new members to replace the two clubs lost to the SPL. Highland League clubs Elgin City and Peterhead were admitted, increasing the total number of clubs in the Scottish football league system to 42.

From 2005, the SFL determined a promotion and relegation place between each division according to playoffs between four clubs. The playoffs were contested between the ninth placed (second bottom) club in the higher division and the second, third and fourth placed clubs in the lower division. It was therefore possible for a team finishing fourth in the Second Division or Third Division to be promoted, rather than the clubs finishing immediately above them in the standings. It was also possible for the ninth placed club to retain their position in the higher division.

In March 2007, a self-conducted review found the league to be three times more expensive to run than equivalent leagues in England, with a report stating the league structure was "outdated". The report found that the Football Conference has four employees looking after 68 clubs, while the SFL had 14 people running leagues with just 30 clubs.

No clubs were relegated from the bottom end of the Scottish Football League, although there were changes of membership due to clubs going out of business. The Scottish Football Association were keen for a pyramid system to be instituted. SFL First Division clubs wanted to gain a greater share of the media revenue generated by the SPL.

In 2013, both the SPL and SFL voted in favour of merging to form the new Scottish Professional Football League. The number of divisions and clubs in each division remained the same, but there were changes to the financial distribution model.

The first club to be promoted to the SPFL from the new Lowland League via playoffs was Edinburgh City in 2016 at the expense of East Stirlingshire, while in 2019 Cove Rangers were the first Highland League champions to go up, replacing Berwick Rangers.

The Scottish Football League organised two knock-out cup competitions: the Scottish League Cup and the Scottish Challenge Cup.

The League Cup was established in 1946, succeeding the wartime Southern League Cup. Unlike the Scottish Cup, organised by the Scottish Football Association, the League Cup was only open to Scottish Football League clubs. Scottish Premier League clubs continued to participate in the League Cup after the top tier clubs broke away in 1998. Until the mid-1990s, the competition winner was eligible to participate in the UEFA Cup, but this was discontinued due to a loss of European places.

The Scottish Challenge Cup was instituted in 1990, to celebrate the League's centenary. The Challenge Cup was only open to Scottish Football League clubs outside the top division of the Scottish football league system.

From 2011, two Highland Football League clubs were allowed to participate each year in the Challenge Cup, to give a round number of 32 clubs participating.

Both the League Cup and the Challenge Cup continued under the auspices of the Scottish Professional Football League.

From 1985, the League accepted sponsorships for its main competition. Below is a list of sponsors and the League's name under their sponsorship:

• 1985–1988: Fine Fare (Fine Fare League)
• 1988–1992: B&Q (B&Q League)
• 1992–1994: No sponsor
• 1994–1998: Bell's Whisky (Bell's League)
• 1998–1999: No sponsor
• 1999–2006: Bell's Whisky (Bell's League)
• 2006–2007: No sponsor
• 2007–2013: Irn-Bru (Irn-Bru League)

The League's cup competitions have had different sponsors, with the Scottish League Cup first attracting sponsorship in 1979. The competition was revamped in 1984, adopting a straight knock-out format, when Skol Lager began its sponsorship. The Co-operative Insurance company sponsored the League Cup for 12 seasons, until the 2010–11 competition.It has since been sponsored by the Scottish Government, under the name of the Scottish Communities League Cup.

The Scottish Challenge Cup was created by League sponsor B&Q in 1990, but it was cancelled in 1998–99 due to a lack of sponsorship. Since 2008, the Challenge Cup has attracted its own sponsor, with BBC Alba and Ramsdens providing support.

Before 1979, the major source of revenue to Scottish Football League clubs, apart from their attendances, was from the football pools. In the year ended 31 March 1983, the pools generated £1.08 million out of a total of £1.46 million. By 1990, this source of income had been overtaken by revenue from sponsorships and television rights. As of 1990, 75% of these central revenues were split equally between the 38 member clubs, with the remaining 25% allocated according to each club's position in the league ladder.

During the 1970s and 1980s, the main terrestrial television companies (STV and BBC Scotland) produced shows (Scotsport and Sportscene respectively) containing highlights of league matches. The revenues from these broadcasts were relatively small, with the companies paying less than £1,000 per match in the mid-1970s. BBC Radio Scotland had exclusive rights for live radio coverage of matches at this time, with independent stations such as Radio Clyde providing coverage via score updates and analysis.

The first live television broadcast of a Scottish league match was not until April 1986. Earlier in the 1985–86 season, there had been no television coverage at all due to a dispute between the League and the broadcasters. The birth of satellite broadcaster British Sky Broadcasting (Sky TV) changed the situation significantly. As ITV had an exclusive contract for live coverage of games in the English league, the first match shown on Sky was a Scottish Premier Division match between Rangers and Dundee United in April 1991.

A year later, the top division English clubs formed a breakaway Premier League, signing an exclusive television contract with Sky. Live Scottish Premier Division games were shown on STV during the 1990s, but the top division clubs formed the breakaway Scottish Premier League in 1998 and signed an exclusive broadcast contract with Sky.

This left the remaining Scottish Football League clubs without live coverage, although STV continued to show highlights of First Division games in their Football First show. Scots Gaelic channel BBC Alba provided coverage of Scottish Football League games, including the Challenge Cup, from its launch in 2008. Live coverage on English language channels returned to Scottish Football League games in the 2012–13 season, as Sky and ESPN agreed contracts to show Third Division matches involving Rangers. These arrangements secured revenues that had been under threat due to the financial collapse of Rangers.

Cowlairs

1893-94