Music education holds an ambiguous relationship to social justice and social change; it is both complicit in perpetuating relations of inequality and a potential force for positive change. There is a need to turn the ambiguity of music's social function--the simultaneous production of transformative and reproductive social processes--into the foundational premise of social analysis of music educational practice. Based on a discussion of ideas derived from social theory, feminist philosophy, and critical musicology concerning the performative constitution of agency and sociality, the notion of ambiguous musical practice is put forward as an analytical lens suited for exploring music's social significance. The notion points to three interlocking dimensions of musical practice: bidirectionality (how music making may at once lead to destabilization and consolidation of social norms); multiplicity of social meanings (how music making produces multiple social meanings and therefore also may produce [contradictory] social effects on different levels of sociality); and in-betweenness (how music making may place participants in a state 'in-between,' understood as a social space where multiple identities, relations, and meanings can be both performed and imposed in ways that render them indeterminate). In this way, the notion of ambiguous musical practice may inform critical social analyses of music educational practice.