WELS does not include the deuterocanonical books in the biblical canon. Following Luther and the Book of Concord, WELS operates with the 66-book canon (39 OT protocanonical books, 27 NT books). The deuterocanonical books (Tobit, Wisdom, Sirach, etc.) are apocryphal — they may be read for edification but are not Scripture or binding for doctrine.

WELS strict confessional subscription includes this understanding of the biblical canon. WELS Bibles include only the 66 protocanonical books. While the WELS recognizes the historical and devotional value of the deuterocanonical literature, it is not part of the church's doctrinal canon.