The purpose of the study was to construct a Leadership Mindset Scale (LMS) and to assess its reliability and construct validity. Participants were 100 employees in a variety of leadership and non-leadership positions at various organizations in three states. An item and factor analysis on the 13 LMS items led to a scale with 11 items (Cronbach [alpha] = 0.80). A Principal Axis Factor analysis with Promax rotation suggested three factors: Leadership Mindset Teachability (LMS-T), a belief in leadership teachability; Leadership Mindset Improvability (LMS-I), a belief in leadership improvability over time; and Leadership Mindset Predictability (LMS-P), a belief that leadership cannot be predicted at an early age. Convergent validity of LMS-Total and Teachability was evidenced by significant correlations with the implicit theories of intelligence and anxiety scales, and developmental leadership and transactional leadership scales. Divergent validity was evidenced by a non-significant correlation with social desirability. The results suggest that the LMS measures a construct different from those of other leadership scales used in the study. The LMS can be helpful in leadership training programs to promote a growth mindset about the trainability of leadership skills.