Abstract Background Children with an obstetric brachial plexus injury (OBPI) can experience problems in the performance of meaningful activities such as writing, bimanual activities, and participation in sports and leisure activities. Aims To quantify the everyday functioning and participation of 7–8 year-old children with an OBPI, with special emphasis on writing, and to investigate associated characteristics. Methods Parents of children with an OBPI were sent a self-report questionnaire regarding the school performance, writing abilities, bimanual hand use, and participation in sports and leisure activities of their child, assessed with the Vineland Adaptive Behavior Scales (VABS sub-scale writing), the ABILHAND-kids, and the Children’s Assessment of Participation and Enjoyment (CAPE). Furthermore, questions were asked about socio-demographic variables, medical history, pain, and the use of assistive devices. Results Fifty three questionnaires were filled in (response 61%). According to the parents, 66% of their children were almost completely recovered, and 58% had a near normal arm function. Most of the children preferred to use their non-involved hand. More than 45% of the children complained about pain, and 39.6% had difficulties with writing, which resulted in a mean developmental delay of 8 months on the VABS sub-scale. Children with writing problems significantly more often had neurosurgery, were living with a single parent, more often received assistance at school, and had a significantly lower ABILHAND-kids score, compared to children with no writing problems. Conclusions Large percentages of 7–8 year-old children with an OBPI experience difficulties with writing and have musculoskeletal pain. Restrictions in participation were less pronounced.