The Greek Matthias (or, in some manuscripts, Maththias), is a name derived from Mattathias, Heb. Mattithiah, signifying "gift of Yahweh."
According to the Book of Acts (Acts 1:15-26), in the days following Jesus' Ascension, Saint Peter proposed to the assembled brethren, who numbered 120, that they choose one among them to fill the place of the traitor Judas in the Apostolate. Two disciples, Joseph Barsabas and Matthias were selected, and lots were drawn. The lot fell on Matthias, who thus became associated with the other eleven Apostles. Matthias was one of the 70 disciples of Jesus, and had been with Him from His baptism by John to the Ascension (Acts 1:21,22).