Each year over two million babies are born very preterm (VP; <32 weeks’ gestational age) and/or with very low birthweight (VLBW; <1500g) worldwide. Despite improved neonatal care, these children remain at high risk for developmental problems later in life. The most common adverse outcomes are social, emotional and attention problems which can impact on a child’s lifelong health and wellbeing. It is therefore critical to understand trajectories of social, emotional and attention problems after VP/VLBW birth to target intervention and improve outcomes across the lifespan. However, although a wealth of data has been collected, there is a paucity of research investigating trajectories of social, emotional and attention development in this population. This project will utilise data from 28 international birth cohort studies, comprising data from an unrivalled sample of 7,053 VP/VLBW participants, the investigators of which have already agreed to data sharing. Novel, innovative statistical techniques will be applied to harmonise different measures of social, emotional and attention problems producing a unique dataset that will allow me to use complex multilevel and longitudinal growth modelling to analyse trajectories from birth to adolescence. The results will advance theoretical understanding of the developmental pathways to social, emotional and attention problems and will have international impact informing the development of clinical guidelines for follow-up care, multidisciplinary intervention, parental counselling and educational policy and planning. The ultimate aim of my proposed research is to improve lifelong outcomes for the growing population of children born very preterm. The training and experience I will gain from working with leading multidisciplinary teams in this field of research will provide me with a unique opportunity to develop myself as an independent academic with the skills, collaborations and expertise needed to become a future research leader.