International research has highlighted teacher leadership as a means to improve teaching and learning by distributing instructional (learning-centered) leadership to teacher leaders. Simultaneously, there has been an increase and alteration of teacher leaders in schools. One example is the 'first teacher' position in Sweden implemented in 2013. The article builds on an inductive, empirical study made in four Swedish schools. I conducted 34 semi-structured interviews with teachers, first teachers, assistant principals, and principals to explore how different school actors understand first teacher leadership and how this enables and constrains the construction of teacher leadership for teaching and learning. In the analysis, I concluded that the participants understand first-teacher leadership as horizontal and facilitative. Their understanding, built on egalitarian and autonomous norms, collides with the intensions of a changed role to improve teaching and learning. The result implies a hidden first-teacher function. In the article, I argue teacher leadership, as a concept, has been forgotten in Swedish research literature and schools, even though Sweden has had teacher leaders for decades. Increased exploration of first-teacher leadership in Swedish schools can contribute to a more visualised and nuanced understanding of teacher leadership and its impact on teaching and learning.