The Department for Children, Schools and Families (DCSF) commissioned NatCen to conduct a project to explore why some young people disengaged from education and underachieved at KS4, assess the longer-term impact of such disengagement and underachievement and consider ways in which it may be prevented or countered. It involved an analysis of matched administrative records to identify young people who underachieved at Key Stage 4 (KS4) relative to their performance at Key Stage 3 (KS3); qualitative research with young people (interviewed between June-August 2008 when they were aged 18-19) and their parents/significant others; and interviews with school staff. Key findings include: (1) Around five per cent of the cohort underachieved at KS4; (2) Profiles of young people's disengagement and underachievement vary across two dimensions--the route by which underachievement occurs (which can be seen as a spectrum from event- or crisis-driven to a gradually occurring process) and the extent to which disengagement occurs; (3) Causes of educational disengagement are wide-ranging, often multiple and inter-related and encompass curriculum and learning style, workload and coursework, relationships with teachers, school and class environments, peer relationships, aspirations and future plans, family context and life events; (4) Schools collected and used information on attendance, attainment and behaviour to identify underachievement and disengagement and a range of support--universal and targeted--was offered to such students in three areas--curriculum, personal support and careers and options advice; (5) Take-up and effectiveness of support varied and a range of factors was involved: the stage at which support was offered, perceived relevance of what was offered, approachability of school staff and young people's relationships with them, timing and location of support, resources, peer relationships; (6) Teachers emphasised the need for more personalised and tailored packages of support and argued for using a more appropriate measure of achievement than the traditional 5 GCSEs at Grades A-C; and (7) Compared to the total cohort, underachievers had distinctive post-16 destinations: they were less likely to be in school, slightly more likely to be in FE or work-based learning, and more likely to be NEET (Not in Employment, Education or Training) or in Jobs Without Training (JWT). Those whose attainment dropped between KS3 and KS4 were more likely to become NEET/JWT than those they had outperformed at KS3. [For the full report, "Pupils with Declining Attainment at Key Stages 3 and 4: Profiles, Experiences and Impacts of Underachievement and Disengagement. Research Report. DCSF-RR086," see ED526913.]