This study explored the relationship between cultural intelligence (CQ) and the leadership style and effectiveness of K-12 principals in US independent private schools from the perspective of the teachers that worked for them. This study provided a mixed-methods framework for examining the perceptions of private school teachers on their principals’ degree of CQ and their leadership. The standardized survey instruments used in this study included the Cultural Intelligence Scale (CQS) observer report, the Measure of Empowering Leadership, and the Leadership Effectiveness Measure. This study found positive correlations between principals' CQ and their leadership style and effectiveness. The study also provided qualitative data that helped explain the basis upon which the teachers in this study assessed their principals’ leadership style.