ABSTRACT On Ecclesiology in “The Holy Spirit and the Upbuilding of the Christian Community” Karl Barth in Dialogue with the Thought of Joseph Ratzinger Michael Haist Jr. This thesis is a dialogue between Karl Barth and Joseph Ratzinger on the topic of ecclesiology. The thesis follows the format of section 67 of Barth's Church Dogmatics, which deals with principles of ecclesiology in the context of the Doctrine of Reconciliation. The question this thesis addresses is whether there is any continuity between the thought of the two figures on certain topics of ecclesiology that are covered by this section of CD. There are several issues on which they agree. On the final topic, Church law, Barth suggests that laws held by different communities can be true despite being potentially contradictory. This paper posits that Ratzinger is in agreement with Barth on this last point.