This qualitative study employed grounded theory to explore how a university-based summer practicum experience with community children (N = 55) revealed and shaped pre-service teachers' (N = 24) understanding of young children and their musical skills and dispositions; how early childhood music curriculum is designed; and supports and barriers to music instruction. We learned that a collaborative professional setting, training and mentoring, and access to developmentally appropriate music curriculum resources scaffolded pre-service teachers' abilities to develop a music unit within the curriculum. These university students gained understanding and appreciation for the music theme's connection to academic content and how music bridged cultural boundaries. We also observed contrasts in students' musical self-efficacy that seemed to be related to their perceptions of the children's musical interests. Continued teacher education research is needed to discern the pre-service preparation that yields curriculum and teaching suffused with rich and joyous music learning experiences for young children.