The Heidelberg Catechism is a document used in Reformed churches to help teach church doctrine. It takes the form of a series of questions and answers to help the reader better understand the material. It has been translated into many languages and is regarded as the most influential Reformed catechism.

Elector Frederick III, sovereign of the Palatinate from 1559 to 1576, appointed Zacharias Ursinus and Caspar Olevianus, to write a Reformed catechism based on input from the leading Reformed scholars of the time. One of its aims was to counteract the teachings of the Roman Catholic Church regarding theology, basing each statement on the text of the Bible.

The Catechism was divided into fifty-two sections, each to be taught one Sunday of the year. The Synod of Heidelberg approved the catechism in 1563. In the Netherlands, the National Synods of the sixteenth century adopted it as one of the Three Forms of Unity, making it requisite for Elders and Deacons to subscribe to, and ministers to teach.

External link to the Catechism online