James the Less is a figure of Early Christianity. He is also called "the Minor", "the Little", "the Lesser", or "the Younger", according to translation. He is not to be confused with James, son of Zebedee ("James the Great"). In most opinions he might be the same person with James, son of Alphaeus, but the sources offer no certainty. In the past, the Western church used to identify him with James, the Lord’s brother ("James the Just")
Identification as James, the son of Alphaeus
The title, "the Less", is used to differentiate James from other people named James. Since it means that he is either the younger or shorter of two, he seems to be compared to one other James. In the lists of the twelve apostles in the synoptic Gospels, there are two apostles called James, who are differentiated there by their fathers: James, son of Zebedee, and James, son of Alphaeus. Long-standing tradition identifies James, the son of Alphaeus, as James the Less. James, son of Zebedee, is then called "James the Great", which is not a name found anywhere in the New Testament. Some propose that Alphaeus was the same man as Cleophas or at least the husband of Mary Clopas.
In this regard, Jerome identified James, the Less with James, son of Alpheus writing in his work called The Perpetual Virginity of Blessed Mary the following:
Do you intend the comparatively unknown James the Less, who is called in Scripture the son of Mary, not however of Mary the mother of our Lord, to be an apostle, or not? If he is an apostle, he must be the son of Alphæus and a believer in Jesus, ‘For neither did his brethren believe in him.’
The only conclusion is that the Mary who is described as the mother of James the Less was the wife of Alphæus and sister of Mary the Lord's mother, the one who is called by John the Evangelist ‘Mary of Clopas‘.
Papias of Hierapolis, who lived circa 70–163 AD, in the surviving fragments of his work Exposition of the Sayings of the Lord relates that Mary, wife of Alphaeus is mother of James the Less:
Mary, mother of James the Less and Joseph, wife of Alphaeus was the sister of Mary the mother of the Lord, whom John names of Cleophas.
Therefore, James, son of Alphaeus would be the same as James the Less.
In Roman Catholic tradition, James's mother is none other than Mary Cleophas who was among the women at the foot of the Cross of Jesus, weeping. For that reason, and given the fact that the Semitic word for brother is also used for other close relatives, James son of Alpheus is often held as a cousin to Jesus. He is also thought by some to be the brother of Matthew the Apostle, since the father of both was named Alphaeus (compare Mark 2:14 and 3:18).
Modern Biblical scholars are divided on whether this identification is correct. John Paul Meier finds it unlikely. Amongst evangelicals, the New Bible Dictionary supports the traditional identification, while Don Carson and Darrell Bock both regard the identification as possible, but not certain.
Identification as James the brother of Jesus
James the Less could also be identified as being James the brother of Jesus (James the Just). Jerome also concluded that James "the brother of the Lord" is the same as James the Less. To explain this, Jerome first tells that James the Less must be identified with James, the son of Alphaeus. After that, James the Less being the same as James, the son of Alphaeus, Jerome describes in his work called De Viris Illustribus that James "the brother of the Lord" is the same as James, son of Alphaeus:
James, who is called the brother of the Lord, surnamed the Just, the son of Joseph by another wife, as some think, but, as appears to me, the son of Mary sister of the mother our Lord <Mary of Cleophas> of whom John makes mention in his book.(John 19:25)
Thus, Jerome concludes that James the Less is the same as James, son of Alphaeus and that James, son of Alphaeus is the same as James the brother of Jesus concluding that James the Less, James, son of Alphaeus and James the brother of Jesus are one and the same person.