This article takes Pope Francis' call for 'a poor church' in Evangelii Gaudium as a starting point for an ecclesiology of vulnerable mission for the church. Drawing from biblical, patristic, and theological sources, the article proposes two theses on the church of the poor, and links these theses with a new model of a vulnerable mission which reflects a humble, servant church which embodies in her teachings and in her inner life and external activities the priorities and practices of Christ in walking with the poor. The paper uses a biblical analysis of the first proclamation of the Lord in the Synoptic Gospels to show that an ecclesiology of vulnerable mission is a way of being church which can help transform the social context. It advances some theological steps which the theologian and the faith communities can take in becoming actively and prophetically involved in co-operating with God in bringing about in particular and group histories the eschatological fruits of God's kingdom. This article takes Pope Francis' call for 'a poor church' in Evangelii Gaudium as a starting point for an ecclesiology of vulnerable mission for the church. Drawing from biblical, patristic, and theological sources, the article proposes two theses on the church of the poor, and links these theses with a new model of a vulnerable mission which reflects a humble, servant church which embodies in her teachings and in her inner life and external activities the priorities and practices of Christ in walking with the poor. The paper uses a biblical analysis of the first proclamation of the Lord in the Synoptic Gospels to show that an ecclesiology of vulnerable mission is a way of being church which can help transform the social context. It advances some theological steps which the theologian and the faith communities can take in becoming actively and prophetically involved in co-operating with God in bringing about in particular and group histories the eschatological fruits of God's kingdom.