Little is known about the changes in self-perceptions over the course of middle childhood, despite this being a crucial period for the development of the self. This study examined stability and change in children's self-competence and self-esteem in a two-wave longitudinal study of primary school children. The influence of psycho-social factors, gender, religion/ethnicity and socio-economic status (SES), on the development of self-perceptions was also examined. A sample of 110 children completed the Harter Self Perception Profile for Children at age 8 and age 11. Analysis of these data indicated considerable stability in children's perceptions of themselves. At age 11, a greater variety of domain-specific self-perceptions was predictive of global self-esteem, suggesting a more complex view of the self. Additionally, between-group differences suggested that girls’ global and athletic competence, as well as their confidence in their physical appearance, decreased over time. Further, children from lower socio-economic backgrounds and those from the minority community in Northern Ireland (Roman Catholics) displayed less positive self-perceptions in a number of life domains at both age 11 and age 8. Discussion of these results highlights the influence of societal factors on children's social development and the need to consider the combined effects of psychosocial identities and socio-economic background on the development of the self.