Teachers' leadership plays a critical and central role in students' educational motivations. This indicates that, in the school context, a teacher's leadership can have both positive and negative impacts on students' educational motivation and performance. This article explores these assumptions, building on the path-goal theory, more specifically the effects of teachers' leadership from students' perspectives. Using a qualitative research design, this study collected data comprising 35 interviews with children and young people in both primary and upper-secondary school. The results show that the degree of teachers' developmental leadership greatly affects students' educational motivation and school performance. Two contrasting teachers' profiles were found: teachers with a high degree of developmental leadership and teachers with a low degree of developmental leadership. Our findings suggest that teachers with the profile of a high degree of developmental leadership create an environment that fosters educational motivation positively among students, facilitating students' achievement of high performance levels and a sense of well-being about their studies. In contrast, we show that teachers with a low degree of developmental leadership create an environment that is nonconductive for educational motivation, performance or the welfare of schoolwork.