He has published in the literary journal of the PEN Club Suisse Romande "L'Escarpe" (renamed 2008 "Pages Littéraires") in 2007–08. A member of International PEN since 1989, he was Secretary-General of the Centre Swiss Romande of PEN PEN Club in 2002–06, and its president 2006–10; 2010-13 he was a member of the centre's executive committee, and in 2013 was again elected president through 2017. Zayas was coordinator of the three Swiss PEN Centres Switzerland 2008–10, and, again, 2013–14. De Zayas served for fifteen years as president of the United Nations Society of Writers, in Geneva.