Distributed leadership alone is not sufficient to bring about the significant changes that are required to improve the quality of teaching and learning in K-12 public schools. Schools that distribute leadership across all levels of the organization must also work to establish collaborative cultures that promote shared beliefs, norms, values, traditions and habits to ensure student achievement and academic success. The purpose of the study was to examine teacher leadership practices in schools with distributed leadership structures and investigate perceptions of teacher leader roles to identify factors that support or inhibit teacher leader success. A mixed-methods approach was used to investigate teacher leadership practice in three schools currently implementing distributed leadership structures. Surveys were distributed to assess school culture and climate. In addition, interviews were conducted with school administrators and teacher leaders to understand perceptions about teacher leadership practice and strategies that support teacher leader success. Findings revealed that schools with distributed leadership structures engage in activities that promote teacher leadership and offer multiple opportunities for teachers to participate in the practice of teacher leadership. In addition, there are commonalities and differences in perceptions about teacher leadership practice and teacher leadership functions outlined in the teacher leader standards framework. [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.]