Survey research has identified, using questionnaire approaches, that important assessments are a significant source of stress and worry for students in secondary school. In particular, failing important examinations and the consequences of failing these examinations are rated as more important than a range of other personal and social worries. Qualitative approaches have gone further in exploring the meaning of these stressful events for students concerned, highlighting themes such as an over-identification with academic success and the perception of GCSE examinations as constituting a crucial moment in determining the future life trajectory of a student. However, this area has been neglected by researchers working on the education-psychology disciplinary boundaries, and a number of important features have yet to be specified regarding the development, antecedents and educational consequences of assessment/examination stress in Key Stage 4 (KS4). The aim of this article is to build on previous work to explore some basic questions surrounding KS4 assessments from a student-centred perspective: (a) what factors lead to the development of assessments in KS4 to be perceived as stressful; and (b) what are the effects for the students concerned? Thirty-four students were interviewed from six secondary schools in the North of England, identified as being likely to experience examinations as anxiety-provoking events and analysed using the principles of grounded theory. Twelve themes emerge structured around a central narrative of "stress, achievement and esteem", which highlighted three key findings. First, stress was linked to the motivation to achieve and the fear of failure through esteem judgments and conditions of acceptance from important others. Second, the experience of stress was linked to a wider educational context including practices and policies pursued by teachers and schools. Third, a more specific state, examination anxiety, was associated with facilitating effects prior to examinations and debilitating effects during examinations. These findings have furthered insights into the developmental antecedents and effects of assessment/examination stress in KS4, and highlighted the need to investigate school/teacher practices and policies and to ascertain the mechanism by which examination anxiety might produce debilitating effects.(Contains 2 notes.