Peter De Mey is Professor of systematic theology at the Faculty of Theology and Religious Studies, KU Leuven. He has been a member of the first steering committee of the Ecclesiological InvestigationsGroup (2006-2010) and co-founder (with Massimo Faggioli) of the Vatican II Studies group of the American Academy of Religion (2012-2016). He publishes about the development of the Catholic view on ecumenism prior to Vatican II, selected documents of Vatican II and current issues related to ecclesiology and ecumenism.