This study investigated if a relationship existed between student achievement in 10th grade Missouri Assessment Program mathematics and 11th grade communication arts scores in 2007 and high school leadership team perceptions of the extent to which they demonstrated leadership practices. The secondary purpose was to compare perceptional differences of the extent to which high school leadership team members demonstrated leadership responsibilities based on intervening variables of gender, position, years of service in the current position, total years of service as an administrator, school enrollment and school location. The study found a significant relationship between the leadership responsibility for order and increased communication arts scores; the study found a significant relationship between the leadership responsibility for knowledge of curriculum, instruction, and assessment and increased mathematics and communication arts scores. For each intervening variable (gender, position, years of service in the current position, total years of service, school enrollment, and school location, there were significant differences in the self-perceptions of leadership responsibilities. Female leadership team members showed a significant difference in perceptions for the leadership practices of relationships, knowledge of curriculum, instruction, assessment, input, and focus. Principals compared to associate/assistant principals showed a significant difference in perceptions for the leadership practices of order, resources, outreach, and affirmation. Leadership team members in years 4-10 of their current position compared to leadership team members with 10 or more years in their current position showed a significant difference in perceptions for the leadership practices of optimizer, ideals and beliefs, and visibility. Leadership team members in years 4-10 of total administrative experience compared to leadership team members with 10 or more years of total administrative experience showed a significant difference in perceptions for the leadership practice of situational awareness. Leadership team members in schools with 1501 or more students showed a significant difference in perceptions for the leadership practices of order and input. Leadership team members in urban schools compared to rural and suburban locations showed a significant difference for the leadership practices of optimizer, order, discipline, input, focus, knowledge of curriculum, instruction and assessment, situational awareness, and intellectual stimulation. [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.]