When an institutional field is stable, the sources of legitimacy - those entities that deem an action appropriate – are relatively easy to identify. However, when institutional fields evolve (Jepperson, 1991) or collective authority tends to be the primary driver of legitimacy (Ruef & Scott, 1998), identifying the source, as well as the criteria, for legitimacy is more difficult. In these situations, the terms for legitimacy may be changing or can be muddled, as no group has an inherent claim in its determination. Therefore, a central issue in institutional studies has become the identification of the sources of legitimacy under these conditions (Deephouse & Suchman, 2008). We analyzed the legitimating accounts in a shifting institutional field, the organic food industry from 1990 to 2011, to consider the following questions: How do actors adapt their legitimating accounts? Is there a discernible pattern? And if so, can they provide insight into the identity of legitimating sources? Results of the analysis indicate actors adapt their legitimating accounts to resonate with sources of legitimacy and that legitimating accounts may provide insight into the legitimating criteria in a field.