This study aimed to develop and validate a theory-based measure of authentic leadership, using five samples from China, Kenya, and the United States. The Authentic Leadership Questionnaire (ALQ) was designed to assess leader self-awareness, relational transparency, internalized moral perspective, and balanced processing. Confirmatory factor analysis supported a higher-order, multidimensional model of authentic leadership. Structural equation modeling demonstrated the predictive validity of the ALQ for important work-related attitudes and behaviors, beyond what ethical and transformational leadership measures offered. The results also revealed a positive relationship between authentic leadership and supervisor-rated performance. The study highlights the importance of authentic leadership in enhancing organizational outcomes and provides a tool for measuring this construct across diverse cultural contexts.This study aimed to develop and validate a theory-based measure of authentic leadership, using five samples from China, Kenya, and the United States. The Authentic Leadership Questionnaire (ALQ) was designed to assess leader self-awareness, relational transparency, internalized moral perspective, and balanced processing. Confirmatory factor analysis supported a higher-order, multidimensional model of authentic leadership. Structural equation modeling demonstrated the predictive validity of the ALQ for important work-related attitudes and behaviors, beyond what ethical and transformational leadership measures offered. The results also revealed a positive relationship between authentic leadership and supervisor-rated performance. The study highlights the importance of authentic leadership in enhancing organizational outcomes and provides a tool for measuring this construct across diverse cultural contexts.