Teacher leadership reflects leadership in schools that is distributed across the organization; is collaborative in nature; and is enacted through a process of influence. Although teacher leadership is important not only in effective school leadership but also in the development, autonomy, and well-being of teachers, existing elementary school organizational structures often do not empower classroom teachers as leaders. The purpose of this qualitative case study was to examine the concept of teacher leadership from the perspectives of elementary school classroom teachers and to explore their perceptions of themselves as teacher leaders. The study sample included 18 classroom teachers from both a public and a private school in the Northwestern United States. Data were collected using semi-structured interviews and a focus group. Qualitative, thematic analysis of interview and focus group transcripts identified five important themes: (1) teacher leadership ambiguity; (2) teacher leadership as formal influence; (3) teacher leadership as a culture of collegiality and collaboration; (4) teacher leadership as individual influence; and (5) teacher leadership as impacted by administrator leadership. Although findings revealed some differences in teacher leadership perceptions between teachers at the public and private schools. almost all of the teacher participants defined teacher leadership as a culture of collegiality and collaboration and described their leadership within that culture in terms of influence. Participant responses indicated that teachers viewed administrator leadership as impactful in relation to their engagement in teacher leadership. Findings suggest that as administrators intentionally establish structures that are supportive of teacher leadership, are present with teachers in fostering their development and autonomy and direct them to each other; teachers feel more empowered to act in and initiate influence as teacher leaders. [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.]