Fifty-years ago in 1969 People and Planning, the Report of the Committee on Public Participation in Planning, was published in the United Kingdom (Great Britain, 1969). Often referred to by the name of the Labour Member of Parliament who chaired it, the Skeffington Report is widely considered a key part of postwar planning history; marking one of the first official attempts to think through how publics could be meaningfully engaged in the production of plans. 1 The same year, of course, also saw the publication of Sherry Arnstein's seminal article on the Ladder of Citizen Participation in the Journal of the American Planning Association (JAPA) (Arnstein, 1969). Fifty years on, 2019 has therefore seen a series of publications and events marking these key moments in the development of contemporary planning theory and practice (see e.g. recent journal special issues: Built Environment, 2019a, 2019b; JAPA, 2019). As Alex Frediani and Camila Cociña argue, in their contribution to this Interface, what we choose to commemorate is always a political act, freighted with cultural significance and weighted by power-relations that determine what is, and is not, worth remembering. In this way, anniversaries matter, as acts of commemoration through which shared understandings and identities are forged. However, there is always a danger that the passage of time leads to the simplification of historical complexity, lending itself to a glib celebration of such milestones as so much evidence of the planning profession's commitment to progressive reformism, rather than prompting a deeper, more critical reflection on their significance. This risk is perhaps particularly marked with regard to public participation, an idea that has become firmly established as a 'good thing' within the ideology of contemporary planning and yet, whose realization fifty-years on arguably remains as elusive and problematic as ever. It was with this in mind that an event was held at the Town and Country Planning Association's offices in London on the 5 th of June, 2019 to: explore the lessons which can be learnt from the experiences of a range of actors and organisations over the decades and set out what will be the likely issues and the changes needed as we move forward into the next 50 years. Attended by around thirty people, most of the contributions to this Interface draw directly on the presentations and discussions that took place on the day. 2