Explored everyday functioning and its relationship to perinatal factors, neonatal morbidity, child behavioural factors and parental socio-economic status for a population-based group of preterm-born and term-born children at six years of age. This population-based study from two county councils in Sweden relies on the national registry data from Statistics Sweden, which includes official statistics for Sweden, the Swedish Medical Birth Registry. Three questionnaires were used: 1) The Strengths and Difficulties Questionnaire; 2) The Performance Skills Questionnaire; and 3) The Interaction Questionnaire. The results show that behaviour problems, here identified as hyperactivity and conduct problems have the greatest influence on everyday functioning in all three groups of children, very preterm, late preterm and full-term.