Reformed theology recognizes two sacraments — Baptism and the Lord's Supper — as signs and seals of the covenant of grace. Baptism is administered to both infants and adults as a sign of inclusion in the covenant community and of the washing of regeneration; it does not automatically confer regeneration but seals the promise to those who believe. The Heidelberg Catechism (Q&A 66–68) describes sacraments as 'visible holy signs and seals instituted by God so that by their use he might the more fully declare and seal to us the promise of the gospel.'

The Lord's Supper is the most doctrinally distinctive Reformed sacrament. Against the Lutheran doctrine of real bodily presence, Reformed theology teaches that Christ's physical body is in heaven at the Father's right hand (Acts 3:21) and cannot be locally present in the bread and wine. However, against Zwingli's bare memorialism, Calvin and Reformed orthodoxy affirm that true believers spiritually and really feed on Christ's body and blood through the sacrament — a genuine reception of Christ, not merely a recollection of his death. The Heidelberg Catechism (Q&A 75–80) and the Belgic Confession (Article 35) articulate this spiritual presence position, which was debated at the Marburg Colloquy (1529) and remained a lasting division between Lutheran and Reformed churches.