This work, entitled "Conception strategies for collective violin teaching in a differentiated classroom," is a qualitative research, based on a methodological approach Research-Action, held in two rounds of research, with the duration of three months each. It was intended to deepen the knowledge about differentiated instruction and its application in vocational education of music – collective instrument teaching (violin). This research was performed at the Center of Musical Culture (CCM), with four 2nd grade violin students. The techniques used for gathering data were, among others, direct and participating observation, field notes recorded in a logbook, the questionnaires and student portfolios. Analysis and interpretation of data was done by analyzing the content of all these records. The aim of this research has been attained and these results confirmed the theory that students learn more with differentiated teaching strategies in collective instrument teaching.