Self-concept—the child's understanding of who they are—develops from concrete descriptions (name, age, physical characteristics) in early childhood to increasingly abstract and psychological descriptions (personality traits, values) in later childhood and adolescence. Self-esteem—the evaluative component—develops through comparison with peers and internalization of reflected appraisals from others. Self-concept becomes increasingly multidimensional and realistic across childhood.
Interview children about themselves at different ages; analyze spontaneous self-descriptions. Measure self-esteem and self-concept using age-appropriate instruments; relate to performance, social feedback, and peer status.
Self-esteem in early childhood is often inflated; realistic self-evaluation emerges later. High self-esteem is not always beneficial; realistic self-appraisal and self-efficacy in specific domains are more predictive of achievement.
Your study of egocentrism and perspective-taking established that children's ability to model other minds develops gradually. The development of self-concept follows a parallel trajectory for a related reason: to know who you are, you must be able to think about yourself from the outside, applying to yourself the same social-cognitive tools you use to understand others. That capacity grows slowly and in recognizable stages.
In early childhood, self-concept is almost entirely concrete: "I am five, I have brown hair, I can run fast." Young children describe themselves in terms of observable, physical, and behavioral features — things that can be directly seen and verified. They almost never use psychological or dispositional language ("I'm patient," "I'm creative"). This is not just limited vocabulary; it reflects that the young child's mental model of self does not yet include stable inner traits as part of identity. The same child who cannot yet attribute stable traits to others also cannot apply that framework to themselves.
Through middle childhood, self-descriptions shift toward the psychological: "I'm a good friend," "I get impatient easily," "I'm better at math than at writing." The concept of trait — a stable internal disposition that predicts behavior across situations — has come online. This mirrors the broader improvement in social cognition: the same advances that let children understand that others have consistent personalities allow them to apply that lens to themselves. The self-concept becomes multidimensional — the child has different beliefs about their academic, athletic, social, and artistic competence — rather than a single global sense of themselves.
Self-esteem, the evaluative component of self-knowledge, develops through two mechanisms: reflected appraisals (how one believes others see them) and social comparison (how one measures up against peers). Early self-esteem is characteristically inflated — young children believe they are good at almost everything and are cheerfully inaccurate. This is not vanity; it is the absence of the comparison framework needed to self-evaluate accurately. Once children enter school and face systematic social comparison — who reads fastest, whose art is praised, who gets picked last — self-esteem differentiates and becomes more realistic. Domain-specific self-concepts emerge: a child may have high academic self-concept, modest athletic self-concept, and low musical self-concept. This differentiation, not a global self-esteem score, predicts outcomes most reliably.