James does not come to us with a clear-cut traditional date, since the book does not mention any historical events or people other than the author in James 1:1. Although strong connections to some of the sayings of Jesus can be seen in verses like 5:12, “let your yes be yes” (compare Matt 5:37), it is probably impossible to say whether or not James has a literary dependence on Matthew or any other New Testament book, so the book’s date stands essentially independent from the rest of the New Testament.
The traditional understanding of authorship is that the book was penned by James, the brother of Jesus and head of the Jerusalem church. Since James was executed in 62 A.D., that would be the latest possible date for the book. Evidence for authorship by this James, as opposed to another Christian by that name or by someone writing in his name, is good. No one else but the head of the Jerusalem church could write a letter to a large audience (“the twelve tribes scattered abroad” – 1:1) and call himself simply “James”, without further clarification. There are also verbal parallels between the book of James and the words of James recorded in Acts 15. Within the New Testament, the salutation used in both passages is unique to James (author to recipients: “greetings” – Acts 15:23, James 1:1). Compare also Acts 15:13 with James 2:5, Acts 15:17 with James 2:7, Acts 15:29 with James 1:27.
Several things are clear from the internal evidence of the book. First, unlike many of the other books of the New Testament which seem to have been written in Rome or Asia Minor, James clearly has a setting in the land of Israel. The term “former and latter rain” (3:7) addresses a weather concern unique to Israel and regions closely adjacent. James is the only book in the Bible outside of the gospels to use “gehenna” for “hell”. Gehenna was a valley outside Jerusalem where trash was burned. Verses like 3:11-12 fit with Israeli geography and farming culture.
The content of James is very strictly Jewish, and some have noted that if verses 1:1 and 2:1 were removed, the book could almost (though not quite) pass as a sermon from a non-Christian Jew. Certainly there is no evidence of any break between Judaism and Christianity. Abraham is described as “our father” (2:21), with no effort made to differentiate between physical and spiritual lineage. The book has no mention of any gentiles. Likewise, there is no mention of any of the issues associated with gentile involvement in the church, such as idolatry, food offered to idols, fellowship between Jewish and gentile Christians, etc. This, as an argument from silence, would seem to date the book prior to the Jerusalem conference of 50 A.D. A date of around 48 would seem reasonable.