Old Catholic theology is the theology that is characteristic of the Old Catholic Churches of the Union of Utrecht. Old Catholic Theology: An Introduction, authored by Peter-Ben Smit, an acknowledged expert in the field, outlines the main characteristics of and influences on Old Catholic theology, as well as the extant ecumenical relationships of the Old Catholic Churches. In doing so, it covers what may be called ‘mainstream’ Old Catholic theology, while paying attention to extant diversity within the Old Catholic tradition. Particular attention is given to the hermeneutical approach to theology, ecclesiology, sacramental theology and ecumenical theology. Old Catholic theology has come to be characterized by a sacramental understanding of the church. This is the result of ecumenical dialogue and the basis upon which the Old Catholic Churches engage in ecumenical rapprochement. Hermeneutics of Scripture and tradition plays an important role as well, given that Old Catholic Churches have developed their own form of a hermeneutics of communion.