Very preterm birth is an important developmental and public health concern, with clear evidence to suggest that very preterm children may be at long term risk of neurodevelopmental impairment and educational difficulties. Although a great deal is known about the neurodevelopmental outcomes associated with very preterm birth,comparatively little is known about the social competence of children born very preterm during the important early childhood period. Therefore, as part of a prospective, longitudinal study, this research examined the social competence of 105 children born very preterm (birth weight <1,500 g and/or gestational age ≤33 weeks) and 108 full term comparison children (gestational age 37-40 weeks) at age 4 years (corrected for extent of prematurity at birth). The aims of this study were 1) to examine the social competence of a regional cohort of children born very preterm and full term comparison children at age four years, 2) to identify infant clinical factors and socio-familial characteristics associated with poor social competence amongst children born very preterm, and 3) to examine the predictive validity of social competence problems amongst both very preterm and full term preschoolers in relation to school academic functioning and behavioural adjustment at age 6 years. At age 4, children were assessed using a range of parent and/or teacher completed questionnaires, spanning emotional regulation, behavioural adjustment and interpersonal social behaviour. Measures included the Emotion Regulation Checklist, the Infant-Toddler Symptoms Checklist, the Strengths and Difficulties Questionnaire, the Behaviour Rating Inventory of Executive Functioning “ Preschool version and the Penn Interactive Peer Play Scale. In addition, as part of a structured research assessment, children completed a battery of false belief tasks and a short form version of the Weschler Preschool and Primary Scales of Intelligence. Two years later at age 6, school teachers qualitatively rated children's behavioural adjustment and academic achievement in math, reading, spelling and language comprehension compared to their classroom peers. Results showed that relative to their full term peers, some children born very preterm tended to score less well across several areas of social competence. Specifically, parent report showed that children born very preterm were more likely to be characterised by higher levels of emotional dysregulation (p=.002) as well as a range of behavioural adjustment problems, spanning inhibitory control problems (p=.03), hyperactivity/inattention (p=.01), conduct problems (p=.01) and emotional symptoms (p=.008). While elevated rates of behavioural adjustment difficulties were also evident amongst very preterm children within the preschool environment, group differences were not statistically significant. However, a statistical trend towards elevated risk of inhibitory control problems amongst very preterm children in the preschool environment was noted (p=.09). Further, children born very preterm were at around a four-fold risk of emotional regulation difficulties of clinical significance,as well as being around 1.5 times more likely to exhibit clinically significant externalising and internalising behavioural difficulties and interpersonal social problems at age 4 years. In contrast, the interpersonal social behaviours and the extent of social cognitive understanding were largely similar across both groups. This pattern of findings remained largely unchanged following statistical control for the selection effects of family socio-economic status. Amongst children born very preterm, significant infant clinical and sociofamilial predictors of both emotional dysregulation and externalizing behaviour were male gender (p=.008/p=.006), neonatal indomethacin (p=.002/p=.005) and elevated maternal anxiety (p=.009/p=.002). Emotional dysregulation was also predicted by low socio-economic status (p=.002). In contrast, internalising behaviour was predicted only by low birth weight (p=.03). Finally, across both groups significant associations were found between overall social competence problems at age 4 years and later school adjustment with those very preterm and full term preschoolers characterised by poor social competence being at elevated risk of a range of behavioural adjustment difficulties and poor academic functioning in reading, spelling and math at age 6 years (corrected). Links between poor social competence and later behavioural adjustment remained across both groups following statistical control for child IQ, while associations with academic functioning were largely attenuated. By age 4 years a number of very preterm children are beginning to display elevated levels of emotional dysregulation, hyperactivity/inattention, conduct problems and emotional symptoms. Further, a substantial proportion of very preterm children may be at risk of developing clinically significant difficulties with these most pronounced in terms of emotional regulation abilities. Children's abilities to regulate their emotions and behaviour represent important building blocks for their later social and emotional functioning. Further, these abilities will likely influence the extent to which children are able to successfully transition to school. Therefore,alongside other important aspects of development, these findings highlight the importance of monitoring the social abilities of preschoolers who were born very preterm across a range of developmental domains and contexts. Preschoolers characterised by emotional, behavioural and/or interpersonal difficulties could then receive targeted intervention aimed at facilitating their social competence prior to school entry.