Idrottsföreningen Kamraterna (English: Sporting Society Comrades), usually abbreviated IFK, is a central organisation for a large number of sports clubs in Sweden. There are also eight IFK clubs in Finland but they are organised separately. It was founded 1 February 1895 and has 164 member clubs with around 100,000 members as of 2004.
IFK was founded in by two young students (Louis Zettersten and Pehr Ehnemark) that wanted to create a sports association, consisting of a main club in Stockholm with smaller clubs in other parts of the country. This was in a time when no nationwide sports organization or other larger associations existed. An advertisement in the youth paper Kamraten (The Comrade) that was published 1 February 1895 called forth all sports interested boys and girls in Sweden to join the society. Less than two months later, clubs in Luleå, Härnösand, Uppsala, Jönköping, Gothenburg and Västerås had been founded, aside the main club in Stockholm. It was decided to name the society after the paper that made the creation possible.
The society grew fast and the administration was too heavy for IFK Stockholm to handle, so a central organisation was created in 1901. Championships and other activities for IFK clubs were arranged and were big tournaments in a time when there existed no central Swedish sports administration to handle nationwide events. Some of these Comrade championships died out as national championships were arranged, but in some sports they live on, for example in Bowling. Other member associations started their own competitions, the most notable being Vasaloppet arranged by IFK Mora and Lidingöloppet arranged by IFK Lidingö.
Aside from the IFK members in Sweden and the separately organised IFK members in Finland, there did also exist IFK associations in Denmark and Norway. The last active member in Denmark was IFK Aalborg that ceased to exist in the early 90s, while the Norwegian member in Kristiania (Oslo) ended its activities early in the 20th century.