Ethnicity remains an essential theory for understanding societies in the 21st century. This paper focuses on how well Fredrik Barth’s 1969 analyses and insights in Ethnic Groups and Boundaries have ‘stood the test of time’. Barth’s theoretical framework sets out the subtle and sinuous frontiers of ethnic boundaries, the interconnectedness of ethnic identities and the continuity of ethnic groups. The messianic nature of this work will be explored by closely reviewing some of his less well cited assertions, including those regarding stigmatized identities, increasing structural similarities and the political organisation of ethnic groups. Considering the applicability of his theory in current times necessitates reflecting on what Barth may have omitted, oversimplified or exaggerated, such as the potential for multiple ethnic identities; the importance of the content of cultural practices, symbols and ‘traditions’; conflict and power plays within nation-states. ‘Looking back’ at Barth’s work on ethnicity assists in enhancing understandings of current social spheres and reconsidering the world around us. It also contributes to the early stages of the author’s current PhD research which includes a focus on Catalan ethnic identity.