The 12th International Polychaete Conference was held from August 1–5, 2016, at National Museum Wales in Cardiff — the first time the conference took place in the United Kingdom. Hosted by Amgueddfa Cymru – National Museum Wales, the event welcomed 198 participants from 27 countries, including 123 researchers and 42 students. The scientific program featured 79 talks across 14 themed sessions and 137 posters covering all aspects of polychaete and annelid research. The conference also included a special tribute publication honoring Kristian Fauchald, a key figure in the founding of the IPC series, and opened with a five-day course on the philosophy of biological systematics led by Kirk Fitzhugh. IPC 12 was both a scientific gathering and a celebration of the community’s history, camaraderie, and shared passion for polychaetes.