BACKGROUND: Cognitive impairments are a hallmark of schizophrenia-spectrum disorders (SSD), contributing to poor treatment outcomes and a key treatment target. The Brief Assessment of Cognition in Schizophrenia (BACS) battery is a validated tool designed to evaluate affected core domains in SSD. The present study evaluated psychometric properties of the German version of the BACS in a representative sample of individuals with SSD and healthy control subjects. RESULTS: All individuals with SSD exhibited significantly lower z-scores across all BACS subtests and BACS composite scores (Z <
-1.5) compared to healthy controls. ROC analysis revealed good diagnostic accuracy with an AUC of 0.83 (95%CI: 0.78,0.88, sensitivity = 0.75, specificity = 0.75). Similar results were observed in sub-cohorts comprising clinically stable SSD patients and those with younger ages (18-35 years old). A unidimensional structure, supported by McDonald's Omega (ω = 0.72) and principal component analysis, confirmed robust internal reliability. CONCLUSIONS: The German BACS demonstrates strong validity and internal reliability when assessed in a representative case-control sample. This study provides an extensive normative dataset for individuals with SSD in German-speaking populations, facilitating future research and clinical assessments of cognition.