Diane Sawyer is replacing Charles Gibson as the anchor of ABC World News, the network announced Wednesday. Gibson is retiring at the end of the year, ABC News president David Westin said, and Sawyer will move from Good Morning America to the evening news in January. After Katie Couric on CBS, she'll be the second solo female to anchor a network newscast. In an email, Gibson revealed that he has been contemplating some form of retirement for several years. "It had been my intention to step down from my job at Good Morning America in 2007 but with [Peter Jenning's] illness, [Bob Woodruff's] injuries, and [Elizabeth Vargas'] pregnancy, the job at World News came open in May of 2006." Gibson also mentioned that he is looking into ways he may continue contributing to ABC News.