This article presents a study of school subject competitions, which are defined as special events where students in primary or upper secondary school have the opportunity to compete against peers in school subjects. The article analyse and discuss characteristics of this educational form across a variety of prominent competitions with a view to identifying types of competitions, and establish how their educational programmes are structured as regards educational themes and didactics. The methodological approach is divided into three phases: 1) a systematic mapping of prominent competitions, 2) a description and synthesis of the educational programmes of the competitions and 3) an analysis and discussion of the data. Systems theory, as presented by Niklas Luhmann, is applied to provide a theoretical framework with regard to the concepts of educational form, didactics, learning, contingency and structural coupling. The findings indicate that the competitions dominantly operate within the three following educational themes: 1) providing an alternative form of teaching subject matter and skills, 2) developing 21st century skills and 3) enhancing excellent students’ learning. The characteristics of the three themes and their didactic approaches are elaborated along with a discussion of the potentials and limitations of school subject competitions as an educational form.