The League of Ireland was founded in 1921 as a single division known as the A Division. The first season featured eight teams, all from County Dublin. The teams that competed in the first season were Bohemians, Dublin United, Frankfort, Jacobs, Olympia, St. James's Gate, Shelbourne and YMCA. The eight founding members had spent the 1920–21 season playing in the Leinster Senior League. Bohemians and Shelbourne had played in the 1919–20 Irish League. St James's Gate were the inaugural champions. Gate also went on to complete a treble having already won both the 1921–22 FAI Cup and 1921–22 Leinster Senior Cup. In 1922–23 the league was expanded to twelve clubs. Among the new members were Shamrock Rovers, who finished as champions, and Athlone Town who became the first team from outside County Dublin to compete in the league. Together with fellow Dublin clubs teams, Bohemians and Shelbourne, Shamrock Rovers would go onto dominate the league during the 1920s and the 1930s. In 1924–25Bray Unknowns and Fordsons became the second and third teams from outside County Dublin to join the league. Fordsons also became the first team from Munster to play in the league. The league continued to expand numerically and geographically during its first two decades of existence. In 1926–27Dundalk were elected to the league and in 1932–33 became the first club from outside County Dublin to win the title. Dundalk were subsequently joined by Waterford in 1930–31, Cork Bohemians in 1932–33, Sligo Rovers in 1934–35 and Limerick F.C. in 1937–38. In 1936–37, Sligo Rovers became the second club from outside County Dublin to win the title. During The Emergency/Second World War era Cork United emerged as the league's strongest team. The club won five league titles between 1940–41 and 1945–46, including three in succession. However they subsequently resigned from the league in 1948. The 1950s was marked by the emergence of St Patrick's Athletic and the re-emergence of Shamrock Rovers. The former succeeded in winning the title at the first attempt in 1951–52 and claimed a further two in the middle of the decade. In 1953–54 the Coad's Colts earned Shamrock Rovers their first title in fifteen years. Drumcondra and Dundalk claimed two League of Ireland titles each during the 1960s but Waterford secured their status as the team of the decade with four league titles, including three in succession between 1967–68 and 1969–70. Six clubs won the League of Ireland title during the 1970s with Waterford, Bohemians and Dundalk winning two titles each. Athlone Town won two league titles at the start of the 1980s but the decade was marked by the four successive league titles won by Shamrock Rovers between 1983–84 and 1986–87. Following the conclusion of the 1984–85 season the league was restructured and the A Division was replaced by the League of Ireland Premier Division.
Second level
The League of Ireland first organised a second level division in 1964–65. The B Division featured reserve teams and emerging senior teams. Although there was no relegation and promotion to and from the A Division, a number of B Division teams, including Home Farm, Bray Wanderers, Athlone Town, UCD, Longford Town and Monaghan United, were subsequently elected to the A Division. In 1985–86 the B Division was replaced as the second level division by the First Division. The First Division featured first teams and a relegation and promotion system operated with the new Premier Division.
Third level
Between 2008 and 2011 the FAI organised a short lived national third level league known as the A Championship. Like the earlier the B Division, the A Championship featured a mixture of League of Ireland reserve teams and emerging senior teams. Unlike the B Division, a promotion and relegation system operated between the Premier Division, the First Division and the A Championship.
Youth leagues
Since 2000–01 the League of Ireland has organised a youth league. It was originally an under-21 league, later becoming an under-20 league, but is now an U19 league. The winners of the overall competition are awarded the Dr Tony O'Neill Cup. In 2015, the League of Ireland also introduced an U17 league. An under-15 league was introduced in 2017, beginning with a truncated season, before fully aligning with the League of Ireland calendar in 2018. An under-13 league is planned to start April 2019.
League of Ireland clubs
2020 Premier Division">2020 League of Ireland Premier Division">2020 Premier Division
2020 First Division">2020 League of Ireland First Division">2020 First Division
League of Ireland games are broadcast by both RTÉ and Eir Sport. In 2014 it was announced that RTÉ will show 78 live Premier Division and FAI Cup games as part of a new agreement with the FAI. The agreement expires in November 2018. RTÉ also broadcast a highlights show, Soccer Republic, throughout the season. In 2015 the FAI agreed a deal with TrackChamp to stream all Premier Division and First Division outside Ireland - though customers criticised this as they had to sign up for a betting account first.
