This ethnographic study examines the development of agency in students with special needs during an experiment of classroom music teaching in a special school. The experiment took place from August 2015 to March 2016 and was based on Emile Jaques-Dalcroze's ideas of music and movement as a means of developing competencies, skills and understanding in music and life in general. The lessons included activities, such as quick reaction and follow exercises, singing with movement, body percussion exercises, dancing, movement improvisation, and relaxation exercises. The data consisted of video recordings of the lessons, and interviews with students, teachers, and teaching assistants. The data were analyzed using qualitative analysis software and thematic analysis. The analysis of the ethnographic data of this practitioner research showed that music-and-movement activities support the development of students' agency by fostering (a) students' own decision-making, (b) interaction with others, (c) expression of emotions and initiative, and (d) being recognized by others as active and able musicians. Consequently, this study encourages educators to advocate music and movement as a tool to support individual agency and active participation inside and outside the classroom.