James writes his letter
James, the brother of Jesus and leader of the church in Jerusalem, wrote to Jewish believers scattered abroad: genuine faith shows itself in works, controlled speech, care for the poor, and patience in trials.
But be doers of the word, and not only hearers, deluding your own selves.
James 1:22 (World English Bible)
The letter is full of echoes of the Sermon on the Mount. It says nothing about the Gentile controversy settled at the council of Acts 15, which suggests to many that it was written earlier, making it possibly the first New Testament book.
Dating notes
Traditionally by James, the Lord's brother (Galatians 1:19). Suggested dates run from about AD 45 to his death in AD 62. The date is an estimate; Scripture doesn't say when the book was written.