Primary generalist teachers face challenges in Music Education relating to skills (Welch & Henley, 2014), self-confidence (De Vries, 2013), and professional identity (Stunell, 2010). Music Education programs build on future teachers’ pedagogical expertise, integrating musico-artistic and didactic practices (Author 1 & Chatelain, 2021) to support meaningful learning. A research project at the HEP-BEJUNE examines music teacher educators’ and primary generalists’ core disciplinary knowledge, revealing shared and divergent understandings shaped by roles and contexts. Teachers and teacher educators draw on varied, adaptable didactic repertoires that blend ways of knowing and being to support learners (Cicurel, 2016). While professional gestures reflect these repertoires (Bucheton & Soulé, 2009), much remains implicit and hard to verbalize (Goigoux, 2007). Initially developed in preservice training and enriched through experience, these repertoires and core disciplinary knowledge evolve through ongoing interplay between theory, practice, and lifelong learning (Perrenoud, 2001). This study aims to identify, analyze, and compare the knowledge of music teacher educators and primary generalist teachers, exploring how this is transferred from training to classroom practice. This study uses the self-confrontation method (Clot & Faïta, 2000) with two Music Education teacher educators from the HEP-BEJUNE and four former students. Each educator films two lessons. The generalist teachers record 45 minutes of Music Education teaching. Self-confrontation interviews are conducted, recorded, and transcribed. Transcripts are coded using the four functions of the present tense in French (Schön, 1983): general truth, narrative, habit, and real-time action (Terrien, Author 3 & Chatelain, 2023). This paper focuses on excerpts coded for general truths, which express core disciplinary knowledge. Thematic categories (Paillé & Mucchielli, 2021) from teacher educator transcripts highlight the importance of bodily and aesthetic experience, the interplay between theory and practice, teacher authenticity and classroom management. Generalist teachers consider music’s place in the curriculum, bodily and vocal expression, and understanding musical concepts. Both groups value musical experience (physical engagement, emotional expression, personal connection) and conceptual understanding (rhythm, melody), and the teacher’s role as a model. However, teacher educators focus on preparing teachers and shaping professional identity, while generalists are concerned with practical challenges like institutional constraints, student performance, evaluation, and fitting music into tight schedules. Examining the gap between core disciplinary knowledge taught in preservice courses and that mobilized by generalist teachers in the classroom can help teacher educators better adapt course content to practical teaching needs.