At one point, James and Jesus’ other brothers attempted to seize Jesus and take him home for a forced retirement. They hoped to keep him from acting and speaking in ways that caused people to say he had gone crazy (Mark 3:21, 31–35).
After Easter, circumstances changed. Paul mentions in 1 Corinthians that the risen Jesus appeared to James (15:7). Then, the book of Acts indicates that the brothers of Jesus were part of the early church in Jerusalem (Acts 1:14) and, apparently, were present for the great event on the day of Pentecost (Acts 2:1–4).
A short while later, James appears to be the leader of the church in Jerusalem (Acts 12:17; 21:18).
From “Getting to Know James and Philip” by Mark Allan Powell, from the May 2015 issue of Gather magazine.