Description: The 'Variations in Teachers' Work, Lives and their Effects on Pupils' (VITAE) project is a four-year (2001-2005) longitudinal study. The key aim of the research was to identify factors which may contribute to variations in teachers' professional and personal lives, and to examine why teachers do, or do not, become more effective over time. Following an initial teacher questionnaire of approximately 7500 teachers, the case study sample was selected and comprised 300 teachers. Half of these were primary teachers (Years 2 and 6) from 75 schools. The secondary teachers taught Year 9 pupils either maths or English in 25 schools. The choice of teachers in Years 2, 6 and 9 was so that the Key Stage national curriculum test results could be used as pupil outcome measures. Methodology: Data were collected through semi-structured interviews with teachers. These were supplemented at various stages of the research by document analysis, interviews with school leaders and groups of pupils. Guided by a critical examination of the literature, an initial questionnaire for teachers was developed. The analysis of data collected from this questionnaire led to the development of interview schedules. Group interviews with pupils were used to follow-up on findings from a pupil attitudinal questionnaire. Measures of teachers' effectiveness as expressed through improvements in pupils' attainment were collected through baseline tests results at the beginning of the school year. These were matched with pupils' national curriculum results at the end of the school year. Data were analysed using either qualitative or statistical aproaches. Once independent analyses were complete, analytical matrices (Miles & Huberman, 1994) enabled the analysis of key 'data cuts'. The areas on which this integrated analysis focused were professional life phases, identity, commitment and resilience. Individual profiles were constructed for each teacher and updated after each round of data collection. The 'qualitative' and 'quantitative' analyses were synthesised and thus contributed to the development of linkages between different features of teachers' work and lives, identities, and their effects on pupil outcomes. Conclusions: Key findings:1. There are associations between teachers' perceived effectiveness and relative effectiveness defined by value-added measures of pupils' progress and attainment.2. There are variations in teachers' work, lives and working contexts which affect their effectiveness.3. The principal factors which moderate effectiveness are teachers' professional life phases and their professional identities.4. Variations in teachers' effectiveness can be identified by investigating individual teachers and groups of teachers in particular phases of their working lives.5. Teachers' sense of positive identity is closely related to their perceived effectiveness. Their capacities to manage their identities in changing life and work circumstances are fundamental to their abilities to sustain effective teaching. 6. Teachers' capacities to manage these are mediated by positive and negative personal, situated and professional factors. The ways these influences are managed affect teachers' commitment and resilience.7. Commitment and resilience are key factors in establishing and maintaining teachers' perceived and relative effectiveness. It is possible to identify patterns of influences which affect teachers' commitment and resilience which will assist in understanding the complexities of teacher's work, lives and identities in particular contexts. 8. Pupils of teachers with high levels of commitment and resilience in all phases of their professional lives are more likely to be higher attaining than those of teachers whose commitment and resilience are lower.9. Teachers who work in schools in more challenging socio-economic contexts are more likely than those who work in less challenging contexts, to face persistent challenges to their commitment, resilience and effectiveness.10. Commitment and resilience are key outcomes of the management of the moderating and mediating influences and these are associated with both perceived effectiveness and relative effectiveness defined by value-added measures of pupil progress and attainment.