This paper explores how primary school children negotiate their musical ideas when inventing musical narratives (Barrett, 2003; Stadler Elmer, 2015)—musical forms that evolve through processes analogous to storytelling, by which children develop linguistic structures. Understanding children’s perspectives offers new insights into how they construct meaning through music, expanding the discussion on co-creativity and agency in music education. Musical invention—the human capacity to organise sounds into symbolic structures (Patel, 2003; Stadler Elmer, 2011)—challenges children’s abstract thinking because of music’s asemantic and symbolic nature (London, 2011). Prior research highlights children’s semiotic abilities to associate sounds with symbolic meanings (Barrett, 2006), as well as the interpretive dimensions of their creative acts (Corsaro, 2000; Campbell, 2002). Adopting a participatory action-research framework (Ferrance, 2000; Kindon et al., 2007), the project involved one class of first-year pupils (ages 7-8) and two classes of third-year pupils (ages 9-10). Small groups (3-4 children) collaboratively invented musical narratives inspired by different objects. Data collection included audio-video recordings of ten creative sessions in each class, during which children wore clip-on microphones to capture their verbal exchanges in detail. Audio-recorded reflections from class teachers and researchers, together with recordings and transcriptions of children’s evolving narratives and performances, complemented the dataset. This paper focuses on children’s dialogues and on how their verbal and non-verbal interactions reveal processes of negotiation and reasoning during musical invention. Qualitative content and video-based analyses (Mayring, 2019; Huber, 2020) were applied to children’s interactions.Findings show that children’s negotiations often led to rich and imaginative explanations that guided the group’s selection of musical ideas. Three main types of symbolic associations emerged. Direct associations linked an object’s material or acoustic quality to an instrumental sound (e.g., a box of beads evoking a shaker’s rhythm). Analogical associations extended meaning metaphorically—such as a belt imagined as a snake, inspiring undulating sounds, or a wooden puppet associated with creating a living being, expressed through glissandi. Embodied associations involved gestures, as when a girl demonstrated “fluidity” with a wide, smooth arm motion that shaped the group’s collective sound. Children’s reasoning and justifications promoted consensus rather than competition, imagination and symbolic coherence foster shared decision-making in musical invention.By foregrounding children’s voices, this study highlights invention as a site for learning musical negotiation, reasoning, and symbolic thinking. Implications include designing pedagogical strategies that value children’s explanations as integral to creative learning, positioning them as active contributors to their musical cultures.