Trust has been identified as key to students' academic improvement. The purpose of this paper is to identify the conditions that build trust in teachers, both towards their colleagues and school leaders, and to explore the emotions triggered among these participants. This study uses the critical incident technique to conduct interviews with 34 teachers from the Valparaiso Region (Chile). Results show that incidents are easily remembered when a subordinate relationship is involved. Many critical incidents are related to situations in which teachers are particularly vulnerable. Hence, teachers value the treatment received and support provided. The arrival of new teachers to a school is crucial when building bonds of trust. Benevolence is the facet that stands out the most in incidents reported by teachers and school leaders, while satisfaction is the most recurrent emotion. In the case of school leaders, benevolence is closely followed by competence. In the case of teachers, benevolence is followed by honesty, openness and competence. In this case, the associated emotion is affection.