Teacher leadership research often focuses on individuals in formal leadership roles, including administrative roles outside of the classroom, attending to their knowledge, skills, and dispositions, and their impact on instructional improvement. An emerging view of teacher leaders focuses on individuals who take on responsibility for instructional improvement in a school or district absent a particular title--often while maintaining a primary responsibility as classroom teacher--and the role that systems play in supporting or constraining teachers' agency and voice in improvement. In this paper, we draw on a networked ecological perspective on teachers' positioning in school systems as well as a dialogical view of identity to present two cases of teacher leaders navigating multiple systems--school, district, and other collaborations and professional spaces--as teacher leaders, negotiating their own conceptions of teacher leadership and their identities as teacher leaders. Through these cases, we offer considerations of how professional spaces in and out of schools and districts can potentially influence evolving perspectives on teacher leadership. We also offer consideration of how identity is key to understanding teacher leader practice and development, as well as attending to influences of various systems on teacher leadership, including particular cultural contexts such as rural schools and communities.