Instructional teacher leaders strive to help teachers build knowledge and skills to improve teaching practice. With titles such as coach or coordinator, they may receive a stipend or released time from teaching. Instructional teacher leaders rely on an array of strategies to improve instruction and enhance student learning. They conduct professional development workshops, co-plan and model lessons, observe teaching and provide feedback, collect and analyze data, facilitate dialogue and reflective critique, and promote shared practices among teachers. Despite the designation as leader, the instructional teacher leader's role is nonsupervisory. Teacher leaders do not evaluate teachers to determine performance-based promotions or sanctions. By maintaining their status as peers rather than supervisors, teacher leaders gain teachers' trust. The logic follows that teachers who trust the teacher leader will seek advice and assistance. The nonsupervisory nature of the teacher leader role creates a paradoxical challenge for the teacher leader. In an effort to gain teachers' trust, teacher leaders deemphasize their status as experts and avoid delivering hard feedback about teaching practice. Yet these actions ultimately undermine the work of improving instruction. How can the teacher leader be both a trusted colleague and a resource for instructional improvement? Making teacher leadership an effective tool for improving instructional practice depends on resolving this paradox. It requires a reconceptualization of the role, placing the teacher leader's expert knowledge at the center of the work. It also requires a school culture that embraces evaluation, collaboration, dialogue, and deprivatization as vital to the instructional improvement process.