AbstractPrevious research suggests that primary–secondary school transitions can be problematic, with some children experiencing a negative impact on academic outcomes and a decline in wellbeing. The negative impact of primary–secondary transition experiences can be long term and lead to young people not completing high school with implications for their subsequent education and employment. However, there are several gaps in existing studies as a result of weak research designs, small samples and the timing of data collection. To better understand children's primary–secondary school transition experiences and the factors which may impact on them, we undertook secondary analysis of data from the Growing Up in Scotland (GUS) study. The analysis focused on data collected when children were in the penultimate year of primary school (Primary 6/P6) and then when they were in the first year of secondary school (Secondary 1/S1). This led to a final sample size of 2559 children and their parents. Results contradict many previous studies which tend to find primary–secondary transitions as overwhelmingly negative. In contrast, we found that 36% of children experienced a positive transition and 42% a moderately positive transition, with only 22% children experiencing a negative transition. This is the first large‐scale, longitudinal and contemporaneous study able to provide a clear proportion of children with positive, moderate and negative transition experiences. Several factors seemed to play a part in children's transition experiences, namely gender, religion, household composition, socioeconomic status, child expectations, schoolwork, and relationships. Implications and recommendations for research, policy and practice have been outlined. Context and implications Rationale for this study: Primary–secondary school transitions are considered to have a detrimental impact on educational and wellbeing outcomes. However, previous studies have several limitations and a more robust analysis of a longitudinal dataset with a large sample was required. Why the new findings matter: This study has highlighted that the majority of children had a positive or moderately positive transition experience. It clarified which factors might influence whether children will have positive or negative transitions. Implications for practitioners, policy makers and researchers: Findings suggest the importance of practitioners and policy makers acknowledging the myriad factors occurring alongside and potentially influencing a child's transition experiences. Similarly, it is important to be mindful of strategies to promote children's positive relationships in both primary and secondary school, especially with their teachers. Further, children's participation in sports, clubs and youth groups should be encouraged. Children's anxieties and misconceptions about transitions should be addressed in a timely manner, including enhanced transition for those with higher levels of concern or anxiety. Fostering and maintaining good school–parent relationships, through timely and relevant communication can facilitate positive transitions.The findings suggest the importance of undertaking research to understand how children from less advantaged socioeconomic backgrounds can be better supported. Similarly, research should be undertaken to understand why some children have negative expectations and are less positive about secondary school. Further, future research should focus on analysing GUS data, including that from S3 and S6, and linking it with administrative data related to attainment and wellbeing.