This article is based on a collaborative research on competency-based assessment in classrooms, led in a French middle school, from 2016 to 2018. Our purpose is to understand better concerns of teachers who have to make assessments without the French system based on a note on 20. We led 1 interview with 5 managers, 4 focus groups with 26 teachers, and collective meetings, led with the methodological approach of «adjusted professional quarrels» from Clot (2006). We have identified six types of teachers’ concerns about competence-based assessment.