The year 2013 will see a big anniversary: 450 years of Heidelberg Catechism. This Protestant confession was written in Heidelberg in 1563 on behalf of Frederick III, Elector Palatine and spread over the world when it was approved on the Synod of Dort in 1619. Since then the Heidelberg Catechism has shaped the spiritual and political life and became a symbol of change and departure from the old in Europe, America, and Asia. Even today the Heidelberg Catechism is the binding confession of the Reformed Church. It is in everyday use by more than 20 million people worldwide. The institutions Palatinate museum Heidelberg (KMH), State Palaces and Gardens Baden-Wurttemberg (SSG), the foundation Refo500 and the Johannes A Lasco Library (JALB) will celebrate the anniversary of the Heidelberg Catechism together in several events. Heart of the activities will be a joint exhibition presented by KMH and SSG in two locations in Heidelberg and the exhibition at Palace Het Loo in Heidelberg, as well as this exhibition book that is realized by Refo500. In addition the Johannes A Lasco Library has supported this project with a conference in March 2011; the conference papers will be included. In this companion to the exhibitions well known specialists in the field present how the Heidelberg Catechism spread and influenced culture, education and ecclesiastical life. Together with over 700 pictures illustrating the contributes and many objects in the exhibitions this documentation becomes an incomparable event!