‘Effort’ and ‘ability’ (understood as potential, intelligence or achievement) are concepts widely used in the everyday language of schooling in Britain but each term lacks clear definition of its use in the school context. Meanwhile, the assessment of effort, alongside that of achievement, remains widespread. This article reports on an exploratory case study of conceptions of effort among three major actors in an English secondary school. Qualitative and quantitative data from questionnaires and interviews with teachers, students and parents at an English comprehensive school were collected. Analysis reveals that understandings of ‘effort’ are not uniform. Rather, ‘effort’ is a shorthand term, which can be used variably, therefore can be construed as a tool of negotiation, or a form of investment in a set of aims distinctive to each group or individual case. There is a strong case for more sustained research into the operationalizing of such key concepts in schools and other professional and workplace settings.