History
This letter does not appear in the Muratorian fragment (2nd century), but it does show up in the Vulgate in late 4th century. It is the Vulgate which became the official canon of the Catholic Church at the Council of Trent. From the start, it was a contentious book.
During the Protestant Reformation, Luther questioned the veracity of the letter, mostly because James places a high emphasis on works as well as sacraments.
Date
The letter was written between 65 and 85AD. Paul had already written his letters and the Gospels were in the process of being written.
General Observations
James is heavily concerned with the issue of poor vs rich.