Assessment has always had a fundamental role to play in education and is carried out in educational establishments to serve a range of purposes. This study examined how teachers in a Sixth Form College in the North East of England operationalise formative and summative assessment with their students in light of the emphasis placed upon high stakes summative testing in the English education system. High stakes testing is frequently associated with a range of unintended consequences, namely the narrowing of the curriculum, teacher-centred pedagogy, and teaching to the test, as students become passive recipients of knowledge in the learning process. In this enquiry, a case study approach is adopted which incorporates 30 lesson observations across a range of A-Level and BTEC subjects and 2 focus group interviews with teaching staff. Three key themes have been identified: formative and summative approaches to assessment and their associated challenges, student actions and responses and changing examination structures. Findings from this study suggest teachers value the embedding of formative assessment into day-to-day teaching practice which should be supported by regular summative assessment. Although time has been identified as an area of difficulty in this regard. Questioning has been highlighted as a key formative assessment tool while other formative assessment strategies such as peer assessment are less popular amongst staff. Teachers attach much value to the promotion of independence amongst their students, particularly following the transition to linear examinations. Furthermore, this research supports previous findings through the identification of a value-practice gap in which teachers work.