This research continued a line of inquiry previously established at Project P.L.A.Y. School, a play-based, Reggio-Emilia-inspired preschool in Elkins Park, Pennsylvania, the purpose of which was to explore what can happen when young children and adults co-construct music in a social, relationship- and play-based environment. Three questions initially guided this study: 1) How does musical content emerge? 2) How is music play developed in this setting? 3) How do children and their teachers story their music experiences? Using narrative and heuristic approaches to inquiry, I, along with my co-researchers, highlighted ways to make children's musical learning audible and visible. Having been a member of this community in the dual role of musical play partner and researcher since fall of 2012, I framed this dissertation study to encompass the weeks of September 16 through December 18, 2014. During that time frame, I increased my visits from once to twice weekly, with fourteen children aged 2.5 through 5 years old, five of whom I knew from the previous year, and five other adults. As both a play partner and researcher, I continued my role as music facilitator who views young children as competent and capable co-music researchers. Amidst other stories, I increased focus as I continued a pedagogy of close listening to children as music co-researchers. Living alongside each other at Project P.L.A.Y. School, children and adults generated and collected shared musical stories. Data sources for this study included audio and video recordings, photographs, artifacts such as artwork and musical notation, and my research notes and journal. I continued using narrative and heuristic approaches to inquiry, and restoried narrative vignettes highlighting children and adults as music co-researchers. From the resulting grand narrative, I found that shifting lenses and all adults mindfully viewing these young children as competent music researchers facilitated and supported children's creative, multimodal expressions of their research interests. Viewing children's and adults' interactions through the lens of co-music researchers lead to abundant, creative musical expression from children and adults alike. Musical content emerged when adults and children interacted as music co-researchers and protagonists in their shared stories. This inquiry generated the following additional questions: 1) How can adults best facilitate young children's musical research interests? 2) How can adults and young children make their collaborative research audible and visible? Implications from this study include encouraging all adults to adopt a pedagogy of listening, to notice and value children's creative musical expressions, and to value children's musical lines of inquiry as researchers. / Music Education / Accompanied by two .m4v files.