Teacher leaders are increasingly leading learning conversations in professional learning communities (PLCs) in schools in several parts of the world today, but there is little empirical knowledge of teacher leadership in PLC conversations. Thus, this article aims to enhance such knowledge, particularly the development of teacher leadership in PLC conversations. Empirical data were acquired in a study of three Swedish PLCs and consisted of six video observations and 24 interviews with teachers and teacher leaders (hereafter 'first teachers'). The study particularly addressed how professional learning and teaching improvement was encouraged in teacher-led PLC conversations, what tended to be missing, and how the conversations influenced the teaching practices of participating teachers (self-reportedly). The results indicate that the teaching practices did not change in depth if the first teachers focused on acknowledging and sharing PLC conversations about concrete teaching methods. Instead, there seems to be a need for informed teacher leaders who consciously and systematically analyse and support teachers' learning processes, and foster a habit of inquiry among their peers. It is suggested that this should include challenging norms and understandings about what it means to be a learning teacher and requirements to improve teaching practices in the long run.