OutMus seeks to understand how different forms of music education affects the student. On the basis of music curricula/legal documents it is obvious that main goals of music education in primary schools are to enable children to experience, reflect on, understand, and participate in musical activities. To fulfill these goals, the development of musical knowledge and competencies are crucial dimensions in terms of learning outcomes. Hence, the project‘s primary objective is the assessment of learning outcomes according to different concepts of music instruction (music lessons centered on the learning and playing of an instrument vs. “ordinary” music lessons in primary school). At the student level, we understand quality as the fulfilment of learning outcomes defined by the curriculum, especially musical competencies. More generally, quality can be viewed as positive effects on music-related and non-musicrelated personal traits (e.g. musical self-concept, social skills) as well as group behaviour (e.g. improved classroom climate). Thus, we ask generally (1) what kind of learning outcomes are achieved by music instruction over one year; and more specifically (2) do variations in the type of instruction cause differences in the amount and structure of the learning outcomes? The “Supply-use-model of teaching and learning” (Seidel, 2014) serves as a theoretical framework for the selection of variables regarding the dimensions of learning opportunities, the individual use of the opportunities, and learning outcomes. The study follows a quasi-experimental 3x3 factorial design, while measurements are scheduled for three time points (pre, post, follow-up) and distributed over 12 months. The design includes two experimental groups (violin vs. dood tuition) and one control group. Data allows to investigate the learning outcome differences between the groups and, moreover, the effect structure and the interactions between the different dependent and independent variables.