This study aims to develop a short German version of the Self Description Questionnaire (SDQ I-GS) in order to present a robust economical instrument for measuring German preadolescents' multidimensional self-concept. A full German version of the SDQ I (SDQ I-G) that maintained the original structure and thus length of the English original SDQ I instrument (Marsh, Herbert W. 1990b. Self Description Questionnaire – I (SDQ I). Manual. Macarthur, NSW, Australia: University of Western Sydney.) served as a basis for empirically deriving the SDQ I-GS. Using a sample of German students in grades 3–6 (N = 1958), the construct validity of the SDQ I-GS was tested by both a within-network approach using confirmatory factor analyses and a between-network approach examining the relations of self-concept to external validity criteria (academic achievement and self-concept factors of another instrument). Construct validity for both the full (SDQ I-G) and the short version (SDQ I-GS) was consistent. Hence, the SDQ I-GS w...