When Sawyer, longtime co-anchor of "Good Morning America," takes over in January, two of three networks will be anchored by women. sawyer ahs certainly earned the honor of anchoring news in a long career at CBS News on "60 Minutes" and at ABC News with various newsmagazines before Good Morning America. The morning show is a solid second in the ratings to NBC's "Today" show.

"There is no one like Charlie Gibson and it is an enormous honor to be asked to join the terrific broadcast he and the great team of journalists have built at 'World News," Sawyer said Wednesday.

"Until then, I'll be getting up early and spending mornings, as always, counting myself so lucky to be with Robin, Chris and Sam and the incredibly smart, talented and dedicated team of 'Good Morning America.'"

"World News" has consistently finished a strong second in the ratings during Gibson's tenure. "CBS Evening News with Katie Couric" finishes a distant third.

"It has not been an easy decision to make" Gibson said in his email to colleagues. "This has been my professional home for almost 35 years. And I love this news department, and all who work in it, to the depths of my soul."

ABC News President David Westin said in a statement that he and Gibson have been talking about the decision for several weeks and that Gibson "has persuaded me that this is both what he wants and what is best for him."

"I respect his decision, just as I respect the enormous contribution he has made to ABC News through the years," Westin said.

"Diane Sawyer is the right person to succeed Charlie and build on what he has accomplished," ABC News Westin said in a statement.

"She has an outstanding and varied career in television journalism, beginning with her role as a State Department correspondent and continuing at 60 Minutes, Primetime Live, and most recently Good Morning America."

Here is the full text of Gibson's email to his colleagues at ABC News:

I have always been taught you should never bury the lead _ so I write to tell you that I have told David Westin I want to step down as anchor of World News, and retire from full time employment at ABC News.

It has not been an easy decision to make. This has been my professional home for almost 35 years. And I love this news department, and all who work in it, to the depths of my soul.

I have received much comment, and quite a few emails and letters referring to the signoff Eddie Pinder convinced me to use - wishing that everyone has had a good day. But the proudest part for me has been saying "...for all of us at ABC News...", since those words signify in my mind that I have been in a position to speak for an entire news department that I consider second to none.

It had been my intention to step down from my job at Good Morning America in 2007 but with Peter's illness, Bob's injuries, and Elizabeth's pregnancy, the job at World News came open in May of 2006, and David asked me to step in as anchor. It was an honor to do so. The program is now operating at a very accelerated, but steady, cruising speed, and I think it is an opportune time for a transition _ both for the broadcast and for me. Life is dynamic; it is not static.

I have told David I would like to continue in some capacity contributing occasionally to ABC News. He has been receptive to the idea - and we will be discussing what that role might be.

Here is David Westin's email to the ABC News staff announcing Sawyer's appointment as the new anchor of "World News."

Today, Charlie Gibson announced to his colleagues at World News that he has decided to step down as anchor effective at the end of this year. I attach below Charlie's full email.

I have asked Diane Sawyer to serve as the next anchor of World News, and she will assume that position in January.

Charlie and I have been talking about his decision for several weeks, and he has persuaded me that this is both what he wants and what is best for him. I respect his decision, just as I respect the enormous contribution he has made to ABC News through the years.

Most recently, he stepped in to lead World News after a difficult and turbulent time _ both for the broadcast and for ABC News over all. We suffered from the loss of Peter and then the severe injuries to Bob. Charlie came to the fore to keep us on the path of doing the first rate journalism that had distinguished World News for many years. We owe him much for the leadership he gave us when we needed it most.

Since then, Charlie has covered all the major events with the substance and grace that we all expect from him. Most importantly, he headed our coverage during a presidential election unlike any other. Now, having accomplished so much in so many different parts of ABC News, Charlie has decided it is time for him to step down. I have told him that he has an open door to continue to work with ABC News, but he's asked for a bit of time before he comes back to us.

Diane Sawyer is the right person to succeed Charlie and build on what he has accomplished. She has an outstanding and varied career in television journalism, beginning with her role as a State Department correspondent and continuing at 60 Minutes, Primetime Live, and Good Morning America.

She has interviewed every President since President George H. W. Bush up to and including President Obama. She has handled an array of breaking news special events, including on 9/11 and, most recently, the presidential election. She has done distinguished documentaries on topics as varied as North Korea, the plight of women in Afghanistan and in prisons here at home, and poverty in Camden, New Jersey, and in Appalachia.

We are fortunate to have a journalist of Diane's proven ability and passion to step into the important position of anchor for World News. She will continue with her documentaries in her new role.

Diane's presence will certainly be missed on Good Morning America. But we are fortunate that both Charlie and Diane will remain with their current broadcasts for the next four months; we will be making further announcements well before any changes are made.