This study presents the validation of the Authentic Leadership Questionnaire (ALQ) in a sample of more than 600 Spanish employees. This questionnaire measures four distinct but related substantive components of authentic leadership. These components are: self-awareness, relational transparency, balanced processing, and internalized moral perspective. Structural equation modeling confirmed that the Spanish version of ALQ has high reliability and predictive validity for important leadership outputs such as perceived effectiveness of leadership, followers' extra effort and satisfaction with the leader.