Across the nation, 48% of schools have failed to meet No Child Left Behind's testing targets (Center of Education Policy, 2011). In 2011, more schools had not made Adequate Yearly Progress (AYP) than in any previous year, according to stateby-state data for the 2011 school year. Out of a total of 980 schools 461, or 47%, did not make AYP in Connecticut in 2011. The term "school improvement plan" is defined by Fidler, 2006, as a commitment document containing evidence that a school improvement system is operating or about to operate in each school. Nationally, most schools have at some point created and attempted to implement a School Improvement Plan (SIP). There is an urgent need for practical SIPs designed to promote school success within the framework of federal mandates. An approach to leadership that encompasses an effective design and implementation of a SIP is needed to ensure that school systems effectively prepare all their community's young people to succeed. The purpose of this case study is to examine how one large, urban secondary school has used a SIP successfully to meet AYP goals and identify characteristics of that school's leadership practices in implementing a SIP. This research used The Vanderbilt Assessment of Leadership in Education (VAL-Ed) assessment. The VAL-Ed assessment for school principals is a theoretically-driven, evidence-based rating scale that assesses principals' behaviors to measure the effectiveness of school leadership behaviors known to influence teacher performance and student learning (Goldring et al., 2008). The findings of this research will be useful in the design, development, and implementation of SIPs aimed at improving student achievement within the context of mandated federal requirements. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]