Douglas starred in Don't Say a Word (2001), filmed shortly before his marriage to Zeta-Jones. In 2003, he starred in It Runs in the Family, which featured three generations of his family (his parents, Kirk and Diana, as well as his own son, Cameron). The film, although a labor of love, was not successful, critically or at the box office. He then starred in and produced the action-thriller The Sentinel in 2006. During that time, he also guest-appeared on the episode, "Fagel Attraction", of the television sitcom Will & Grace, as a gay cop attracted to Will Truman (Eric McCormack); the performance earned Douglas an Emmy Award nomination for Outstanding Guest Actor in a Comedy Show.
Douglas and Zeta-Jones hosted the annual Nobel Peace Prize concert in Oslo, Norway, on December 11, 2003. They acted as co-masters of ceremony in the concert celebrating the award given to Iranian human rights activist Shirin Ebadi. In 2006, Douglas was awarded an honorary Doctor of Letters (D.Litt.) from the University of St. Andrews in Scotland.
A few years earlier, in 2003, Douglas hosted a "powerful film" on child soldiers and the impact of combat on children in countries such as Sierra Leone. During the documentary film, Douglas interviewed children, and estimated that they were among 300,000 other children worldwide who have been conscripted or kidnapped and forced to fight. Of one such child he interviewed, Douglas stated, "After being kidnapped by a rebel group, he was tortured, drugged, and forced to commit atrocities." Douglas discussed his role as a Messenger Peace for the UN: