We present evidence that New Urbanism, defined as a set of normative urban characteristics codified in the 1996 Charter of the New Urbanism, reached a seminal moment—in mission if not in name—with the 2016 New Urban Agenda, a landmark document adopted by acclamation by all 193 member states of the United Nations. We compare the two documents and find key parallels between them (including mix of uses, walkable multi-modal streets, buildings defining public space, mix of building ages and heritage patterns, co-production of the city by the citizens, and understanding of the city as an evolutionary self-organizing structure). Both documents also reveal striking contrasts with the highly influential 20th century Athens Charter, from 1933, developed by the Congrès Internationaux d’Architecture Moderne. Yet, both newer documents also still face formidable barriers to implementation, and, as we argue, each faces similar challenges in formulating effective alternatives to business as usual. We trace this history up to the present day, and the necessary requirements for what we conclude is an ‘unfinished reformation’ ahead.