Educators have known for generations the significance of teaching youngsters to read, but have turned their collective attention in only the past decade or so to the state of inadequate reading in high schools. The view is alarming by many accounts and has led national organizations to urge high school principals to add yet another responsibility to their growingly complex set of duties: to serve as "literacy leaders." This study used a mixed-methods, multiple-case study to identify the literacy-related practices and beliefs of principals in three high schools in Connecticut with statistically significant reading improvement. Among findings common to all three schools were the following: administrators and teachers reported that they valued collaborative leadership the most of five literacy-related practices framing the study; and in two of the three schools staff members described their principal's leadership style as highly collaborative, the style advocated in professional literature on literacy leadership. That the third principal was not described as collaborative and yet led a school with significant student improvement suggested that more than one leadership style could be effective. In all three schools, principals shared literacy leadership with a key administrator, their respective English Department leader, and they supported efforts to infuse literacy strategies across disciplines. In addition, the principals all supported an ongoing professional development program devoted to literacy that built staff skills over several years. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]