Östers Idrottsförening, commonly known as Östers IF or simply Öster, is a Swedish sports club located in Växjö, specializing in football. For the 2025 season the club is back in the top tier, Allsvenskan, after achieving promotion from Superettan in 2024. It will be the club's first season in Allsvenskan since 2013.

The club has previously also competed in ice hockey (see separate article), bandy, and bowling. Öster was formed on 20 April 1930 as Östers Fotbollförening, before adopting the name \"Östers IF\" in 1932. The club is affiliated to the Smålands Fotbollförbund.

In 1968, their first season in Allsvenskan, Öster became the first team ever to win the national title at their first attempt (newly promoted IF Elfsborg won the league in 1961 but had played in, and been winners of, the championship in the past). This win ignited the team's 'golden age' which lasted until the early 1980s and saw them win a total of four Swedish championships.

On 31 March 2011, Öster broke ground on their new arena, Myresjöhus Arena, which was inaugurated in August 2012. The arena hosted four games of the UEFA Women's Euro 2013 tournament.