Charlie Gibson Being Replaced by Diane Sawyer on 'World News Tonight'

"World News Tonight" anchor Charlie Gibson is stepping down to make way for his former "Good Morning America" co-host Diane Sawyer.

ABC News announced Wednesday that Charlie Gibson will leave "World News" in January, and that Diane Sawyer will be the new anchor of the network's evening newscast.

Sawyer's elevation means that, with Katie Couric, two of the three leading anchors for the broadcast networks will be women.

Gibson, 66, took over the anchor chair at "World News" in May 2006, after anchor Bob Woodruff was seriously wounded in an IED attack in Iraq. He said he had been planning to retire at the end of 2007 but events compelled him to stay.

Gibson has been at ABC News for 35 years and says he plans to continue as an occasional contributor.

Gibson enjoyed a ratings lead shortly after he took over "World News." But he was eventually passed by NBC's Brian Williams, who has led in the ratings for nearly a year.

The Associated Press contributed to this report.