The German-speaking research landscape lacks a verifiably validated measure of authentic leadership. We aimed at closing this gap with a German adaptation of the Authentic Leadership Inventory provided by Neider and Schriesheim (2011). We tested and adapted the translated DIAF (Deutsches Inventar Authentischer Führung) in three samples (N_total = 705). Confirmatory factor analysis confirmed the expected four component-structure: self-awareness, relational transparency, internalized moral perspective, and balanced processing. The overall scale (16 items) and the subscales had good to excellent internal consistencies. As expected, the DIAF was significantly related to other leadership scales (i. e., positive correlations with ethical leadership and leader member exchange, negative correlations with destructive leadership). The measure correlated significantly with criteria of organizational performance (i. e., well-being, work engagement, individual performance) and showed incremental validity above and beyond other leadership scales. In sum, the DIAF provides a viable and valid measure for assessing authentic leadership.