MySpace, the country’s largest social-networking Web site, has agreed with attorneys general of 49 states to take new steps to protect children from sexual predators on its site. It also agreed to lead a nationwide effort to develop technology to verify the ages and identities of Internet users, officials announced Monday.

The agreement is the latest attempt by law enforcement officials nationwide to shield children from online dangers, including the risk of encountering inappropriate sexual content or receiving sexual advances through sites like MySpace and Facebook. The sites, increasingly popular among college, high school and even younger students, allow any Internet user to create a profile to display personal information and build networks of friends online.

Richard Blumenthal, the Connecticut attorney general, announced the deal at a news conference in Midtown Manhattan, along with a MySpace executive and Roy Cooper, the attorney general of North Carolina. Also present were Attorney General Anne Milgram of New Jersey and the attorneys general of Pennsylvania and Ohio.

Mr. Blumenthal said the voluntary agreement went further than the one struck in October between New York’s attorney general, Andrew M. Cuomo, and the Facebook Web site.

“It’s stronger, broader, a very significant step or even a milestone in making the industry aim higher to keep kids safer,” Mr. Blumenthal said in an interview.

He cited steps in the new agreement to separate children’s profiles from those of adults and to seek ways to verify users’ ages — steps that he called for after the Facebook agreement, when he and Mr. Cooper had said that stronger measures were needed.

Mr. Cuomo said the MySpace agreement built on Facebook’s acknowledgment that it bore responsibility for protecting users.

“The Facebook agreement broke the ice,” he said.

The most important new measure, Mr. Blumenthal said, is that MySpace will create and lead a task force to find ways to verify ages and identities online. The task force, which will receive input from competing sites, child protection groups and technology companies, will report back to the attorneys general quarterly and issue recommendations at the end of this year.

Facebook, in its agreement with New York prosecutors, promised to respond more speedily to complaints about sexual messages and to warn users in stronger language that the site could not guarantee children’s safety.

The new agreement with MySpace, signed by 50 attorneys general — the top prosecutors of the District of Columbia and every state except Texas, includes similar provisions, and more.

“This is an industrywide challenge, and we must all work together to create a safer Internet,” Hemanshu Nigam, the chief security officer of MySpace, said in a statement.

MySpace, which says it has about 70 million users, agreed to install safeguards that require an adult user to prove that he or she knows a child user in order to contact that child, for instance by typing in an address or phone number.

Profiles of users under 18 will automatically be set to “private,” preventing casual browsers from seeing them.