The 'Ramsar' Convention on Wetlands was the first of the modern era global biodiversity conventions and remains the only multilateral environmental agreement focused on a single group of ecosystem types. At the time of initial discussions within the wetland conservation science community in the late 1960s, its ambition was unprecedented, with no successful models to draw upon, especially with regard to novel concepts such as the modus for an 'internationally protected site'. Drawing on previously unpublished draft texts, we track the Convention's textual development to its ultimate agreement in 1971. During this period its geographic scope changed from an initial European to global focus, whereas core obligations related to the designation of internationally important wetlands and the provision of secretariat coordination functions were substantively developed. We present (as supplementary material) all draft texts, from 1965 to 1971, previously unavailable online.