The PCA affirms the Protestant biblical canon of 66 books: 39 Old Testament books and 27 New Testament books. This canon consists of the Hebrew Old Testament (in its traditional order) and the New Testament writings recognized by the early church and confirmed by subsequent councils.

The books of the Apocrypha (Deuterocanonical books in Catholic and Orthodox bibles) are recognized as historically valuable but are not considered part of inspired Scripture. The canon is closed—no new books are being added to Scripture, and no apostolic authority figures remain to authenticate new writings.

The PCA affirms the principle of sola scriptura: Scripture alone is the norm for doctrine and practice. The canon was not determined arbitrarily by church councils but recognized by the church as books that bore the marks of apostolic authority and were universally received. The sufficiency of Scripture grounds Reformed resistance to additional authorities (Sacred Tradition, papal declarations).