The importance of a positive self-concept as an educational outcome and a facilitator of other desirable outcomes are well established within the education research field. Although the multidimensional and hierarchical model of the self-concept is widely accepted within the educational psychology, this perspective is not widely used within the mental health research. Hence, the purpose of the present investigation is to compare the psychometric properties of the short version of the Self-Description Questionnaire (SDQII-S) based on responses by a large sample of female adolescent high school students (N= 829) and a clinical sample of adolescent girls who have been diagnosed with anorexia nervosa (N= 75). The well-established psychometric properties of the longer version of the SDQII generalise well to both samples of adolescent girls, and analyses provided good support for the invariance of the factor structure across the two samples. Furthermore, analyses employing new structural equation modelling approaches to comparing the latent mean differences indicated that there were differences (although surprisingly small) between the two groups that were generally consistent with a priori predictions. The important educational and clinical implications of these results are discussed.