Diagnostic information is a centrepiece of educational decision making. Far-reaching decisions like placements within multi-tiered school systems may have a huge long-term impact on the achieved level of education. Therefore, such decisions should be substantiated or complemented by objective and prognostically valid information. To this end, we assessed academic self-concept, reading comprehension, orthographic abilities, and geometric and problem-solving skills prior to the selection of subsequent school forms in Grade 4 in order to model the pedagogical decisions of the teachers (Lenhard, Hasselhorn, & Schneider, 2011). The article describes the longitudinal results of an independent sample of 76 students and how well their academic performance was predicted 18 months later by the psychometric approach compared to teacher recommendations. Standardized tests had a high prognostic validity and predicted the choice of higher educational levels in subsequent school years. Teachers were more successful in determining grouping decisions for students with lower educational attainments.