Yahoo and Bebo announced today that Yahoo will sell display advertising for the social-networking site. The deal is the first of its kind Yahoo has secured with a social-networking site, the companies said today.

The agreement marks a significant milestone for Yahoo, whose turbulent management troubles and sagging revenues have left it chasing Google and Microsoft for a slice of growing online advertising revenues.

Under the deal, Yahoo will sell the majority of Bebo's display ads for the UK and Ireland, reaching around 11.6 million users per month, the companies said, siting traffic statistics from comScore Networks. About 75 percent of the UK's internet users visit Bebo, particularly 13 to 24-year-olds. Bebo was founded in January 2005.

Yahoo already supplied search for Bebo. No information was released on how much either company will make from the deal. The new features should be visible later this year.

Yahoo and Bebo also plan to develop a toolbar that will enable Bebo users to monitor activity on the site even when they are not actively viewing it. Bebo will also weave into its site Yahoo's Answers feature, a bulletin-board type service where people answer each others' questions and rank those answers based on quality.