<p> Today's nurse leaders face many challenges and concerns that require a new type of leadership &mdash; authentic leadership. Nurse leaders who are authentic are behaviorally altruistic, transparent, have personal integrity, possess attributes of caring, ethical moral values, shared and balanced decision making, effective communication, and integral relationships. The purpose of this research was to explore, develop and validate an instrument measuring perceived authentic leadership, by staff nurses, that is grounded in a nursing theoretical framework that supports clinical practice and knowledge development. In addition, to validation of the instrument, hypotheses investigated in this research examined the extent in which the Authentic Nurse Leadership Questionnaire, is supported by the Authentic Nurse Leadership conceptual framework, and its relationship between authentic nurse leaders' attributes, nurse engagement, and nurse work-life. The methodology included Polit and Beck's method of multi-item scale development. A cross-over design was employed to compare the Authentic Nurse Leadership Questionnaire, this new instrument, with Authentic Leadership Questionnaire was implemented in the pilot and full study phase. Sample included: an expert panel (n =19) which included clinical nurse leaders, faculty and researchers, pilot study (n = 20) registered staff nurses and full study (n = 309) registered staff nurses who provide 50% or more direct patient care. Study results indicated: the average Content Validity Indices (CVI) for the final 29-item scale, its subscales and individual questions, all surpassing the .9 bench mark. The Cronbach's alpha coefficients ranged from .89 to .99, and the Intra Class Coefficients (ICCs) for 3 week test-retest reliability from 0.87 to .94. Findings indicated the ANLQ was reliable and valid instrument to measure authentic nursing leadership. Overall the ANLQ demonstrated better nursing values as indicated by a stronger relationship with nursing areas of work-life and nurse engagement than what ALQ did. The ANLQ concepts were statistically supported by both exploratory and confirmatory factor analyses. Nurse leaders who incorporate Authentic Nurse Leadership into their practice are uniquely positioned to influence nurse work-life environment and nurse engagement.</p>