Basic motor competencies (in German: Motorische Basiskompetenzen; MOBAK) are motor performance dispositions formulated as minimum standards that empower children to participate in the culture of human movement. In opposition to movement-specific and process-oriented fundamental movement skills assessing the quality of movement execution, basic motor competencies are context-specific and product-oriented and focus on the mastery of minimum motor demands. Consequently, the promotion of basic motor competencies is a central goal of physical education, as they are essential prerequisites to be able to develop a physically active lifestyle. For the diagnosis of basic motor competencies, teachers need valid survey instruments that can help them to adapt their didactic-methodical action. For this purpose, a test battery for the assessment of the basic motor competencies of third graders was developed (MOBAK-3) and subjected to empirical validation (N = 399; 50.4% female; M = 8.45 years, SD = 0.52). The exploratory structural equation modeling indicates a structure with three factors named "Locomotion," "Object-control" and "Moving in water". This structure could be confirmed in the confirmatory factor analysis (CFI = 0.998; RMSEA = 0.009) and there was no differential item functioning (DIF) between boys and girls and the age. Furthermore, the sensitivity of the test instrument with regard to pedagogical diagnosis was confirmed based on a normative definition of support needs in motor competence. The MOBAK-3 test battery satisfies the requirements of test theory and is suitable for an analysis of basic motor competencies and the identification of motor deficiencies in students.