Continuing a series of posts calling attention to selected resources featured in Appendix 1, "Resources for Ecumenical Engagement," in Ecumenism Means You, Too: Ordinary Christians and the Quest for Christian Unity (Cascade Books, 2010):
Nicholas Lossky (ed.), Dictionary of the Ecumenical Movement (2nd ed.; Geneva: WCC Publications, 2002) is a helpful reference work for those seeking to learn more about ecumenism, featuring entries on all aspects of the ecumenical movement as well as the churches that belong to the divisions of the one church, written by internationally recognized ecumenists and experts on each Christian denomination/communion.
Interested in Ecumenism Means You, Too? Order the book directly from Cascade Books or via Amazon.