As head of the Department of Pedagogy at the University of Chicago, John Dewey established an elementary school where a new curriculum could be put into practice, evaluated, and refined. This paper discusses how the activities of the school put Dewey's theories into practice generally, and particularly how they were applied to music education. Dewey's published works and the contemporaneous notebooks of teachers at the Chicago Laboratory School are the main sources for this analysis. Following Dewey's theories, teachers used constructive activities as the medium for cultivation of the children's imagination; children were encouraged to express their ideas through various modes. Dewey found evidence for stages in mental development in young children beginning with an early imaginative stage, later becoming experimental, reflective thinking. Children's musical intelligence was seen as developing through their ability to form and express mental images of musical wholes. Images then became the tool of instruction. Once simple melodies and words were grasped as thought expressed in musical form, then ideas could be expanded into their essential elements: melody, rhythm, and harmony, moving from simple to complex. Group composition was encouraged as it combined action and reflected the children as social individuals. Young children were encouraged to express their ideas in multiple ways, to question, and to try new learning experiences. (Contains 39 references.) (JLS)