The role of a principal has changed drastically over the past several decades. Principals must now be able to instructionally support their teachers to provide equity of learning for all students. The purpose of the phenomenological qualitative study was to determine key instructional leadership characteristics and styles that principals perceived to be most effective in supporting and promoting positive student achievement. To discover answers to this study's hypothesis, ten Indiana principals representing K-12 public schools were interviewed, plus five Indiana superintendents participated in a focus group. The school leaders were interviewed to identify key leadership characteristics and styles that defined a highly effective principal. This study found five focus themes listed in order of occurrence: "instructional leadership," "curriculum and academic standards," "data-driven instruction," "positive culture and climate," and "engagement." This research shows the need to support principals by continually improving their leadership skills since highly effective instructional leaders do impact positive student achievement. [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.]