Effective principals impact student achievement, and a principal's and followers' perceptions are indicators of effectiveness. Principals may not be unaware of, or fully understand, the relationship between their leadership effectiveness, priorities, and optimal competencies and behaviors. Even with numerous demands on a principal's time, often from unwelcome priorities, some principals are effective. The problem was a need to find out what these effective principals do to navigate the bombardment of demands yet maintain their effectiveness and impact on student achievement. This understanding may prevent achievement from being hindered by choosing unsuitable, non-obligatory, priority focus areas. Contingency leadership theory in education framed this study. Contingency theory matches leadership competencies and context. The research question is: What are the priorities and accompanying competencies and behaviors of an effective international school principal as perceived by the principal and their followers? This qualitative study examined the perceived priorities, competencies, and behaviors of an effective international school principal and six educators they supervise. Effectiveness was based on student achievement on a repeated, standardized assessment. The principal was effective in improving student achievement as he addressed his priorities--regardless of what he spent his time on--successfully matching the context of the school with competencies and behaviors. His leadership style was predominantly servant leader-driven with some of the characteristics of distributed leadership, transformational leadership, and Total Quality Management. International or aspiring leaders may reference this study for concrete examples of priorities, competencies, and behaviors an international school leader implemented to be effective for guidance and learning. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]