Since 1982 all editions of the Book of Mormon have appeared with the subtitle: "Another Testament of Jesus Christ."
At that time Church leaders felt a need to further emphasize the purpose of the book as stated on the title page: "...And also to the convincing of the Jew and Gentile that JESUS is the CHRIST, the ETERNAL GOD, manifesting himself unto all nations...""With the subtitle added to the Book of Mormon, the purpose of the book, 'to the convincing of the Jew and Gentile that JESUS is the CHRIST,' will become immediately apparent to all who hereafter receive the Book of Mormon," said President Ezra Taft Benson, then president of the Council of the Twelve.
Additionally, according to Elder Boyd K. Packer of the Council of the Twelve, the subtitle clarifies the Book of Mormon's place among scriptures. He said in an interview at that time: "The Book of Mormon has been misunderstood. With the subtitle, it takes its place where it should be-- beside the Old Testament and the New Testament."
The subtitle, approved by President Spencer W. Kimball to put the purpose of the book "in full view," was announced in an address by Elder Packer at the October 1982 general conference.
Since that time all paperback and hardback editions of the Book of Mormon have had the subtitle prominently displayed on the cover and on the first inside page. In the triple combination the subtitle appears on title pages just inside the cover.
The addition of the subtitle capped an ambitious 10-year effort with the scriptures that included publication of new editions of all Standard Works, a much-expanded Topical Guide with cross-references between all four books of scripture, and new chapter and index entries.