The transition from primary to secondary school represents a significant rite of passage for many young people in the UK every year. However, this transition has been linked to negative educational, social and emotional outcomes for some pupils. To date research has considered the impact of individual differences on adjustment to secondary school in terms of single risk and protective factors, with little consideration of the interaction between them. A key aim of this study was to better understand the characteristics of pupils who are vulnerable to negative outcomes during the primary-secondary transition. The current study considered multiple risk and protective factors together within a framework of resilience in order to investigate which pre-transfer factors were most predictive of post-transfer school adjustment outcomes, assessed one term after transfer to secondary school. The study also explored the combined impact of pre-transfer risk and resilience factors upon secondary school adjustment by investigating possible moderator relationships. A second aim of the study was to understand in more depth the experiences of pupils already identified as vulnerable during transition. A mixed method design was adopted, comprising two distinct stages. Within the first stage, pupils completed questionnaires rating their resilience and school adjustment both pre and post-transfer. In total 133 pupils completed questionnaires at both time points. Teachers also rated the pupils' school adjustment and resilience at these times and further information on pupil risk was collected via demographic information from school records. During the second stage of the study, semi-structured interviews were carried out with a subgroup of pupils identified as vulnerable based upon risk factors prior to transfer. Overall, the study found that predictors of less successful teacher-rated school adjustment after transfer related to poor behaviour, low maths attainment and limited problem solving abilities in primary school. Less successful pupil-rated school adjustment outcomes were predicted by perceptions of low levels of support and problem solving skills, as well as difficulties in controlling emotional reactions and maintaining emotional stability prior to transfer. The study also highlighted the potential complexity involved in supporting pupils with SEN during transition. The findings suggest that additional support in primary schools alone leaves SEN pupils less prepared for the significant changes they face in their new secondary schools. Finally, the semi-structured interviews revealed largely positive experiences of transfer, suggesting that risk factors alone are insufficient in identifying vulnerable pupils at transition.