Literature on categories recognizes that in the early stages of a category, ambiguity can arise from divergent frames used to define the category. Yet it also largely expects this ambiguity to be either temporary, or else detrimental to the survival and evolution of the category. In this study, we demonstrate and explain how, alternatively, category ambiguity can persist when multiple frames continue to be applied to a category as it progresses into maturity. Drawing on an in-depth qualitative study of the case of social entrepreneurship, we examine how and under what conditions this outcome occurs. We specify two co-occurring conditions that prompt category stakeholders to shift their framing from exclusive to inclusive, enabling category ambiguity to persist. We furthermore show how the use of category frames that draw from pre-existing resonant categories supports the persistence of category ambiguity. We contribute to literature on categories by clarifying the antecedents of category evolution towards a trajectory of persistent ambiguity.