As an addendum to an earlier posting – Where the Bible Came From – I offer the following insight from the late Jaroslav Pelikan, who was Sterling Professor Emeritus of History at Yale University:
As part of the Septuagint “canon,” the Apocrypha became and still are part of the Christian Bible in both the Eastern Orthodox and the Western Roman Catholic churches. They continued to hold this position, though without definitive and formal church legislation according it to them, until the Reformation churches assigned them (at best) second-class status, on the grounds that they were books which “the church doth read for example of life and instruction of manners, but yet doth it not apply them to establish any doctrine.” For most of Christendom during most of Christian history, however, they were and still are simply part of the Bible.
This quote is taken from Pelikan’s 2005 book Whose Bible Is It?: A History of the Scriptures Through the Ages, page 72 (emphasis added).
So you can see that in the 16th Century, it was Protestants who removed these books from the Old Testament, not Catholics who added them.