Though there is no direct mention of celestial marriage in the Book of Mormon, it is inconceivable that such blessings were not available to the people who were worthy of them (see commentary on 4 Nephi 1:11). We would assume, also, that inasmuch as the fulness of the gospel (and the fulness of gospel ordinances) was had by the Nephites, baptisms for the dead were practiced just as they were in the Old World (see 1 Corinthians 15:29). The record is, however, silent on the matter.