Gordon Brown is seeking to get thousands of young people to sign a pledge against knife crime.
The prime minister is backing the launch of an online anti-knife crime which is trying to promote efforts to tackle serious youth violence by getting teenagers to sign the Count Me In pledge on Facebook.
Advice, routes to further support and testimonies from those affected by knife crime are featured on the website and that of the charity behind it, Families Utd. Extra classroom materials are also being provided.
"I believe young people want to see an end to knife crime, just as we all do, and I believe the power to make that happen is as much in their hands as it is ours," Mr Brown said.
"So this week we're asking them to sign the pledge and say 'Count Me In' to a world without knife crime."
Schools minister Vernon Coaker pointed out that the government had helped reduce knife crime, but said it could not "solve the problem completely".
Home secretary Alan Johnson pressed the importance of education and prevention.
"This week is a great opportunity for young people to take a stand against the small minority who commit these serious crimes and spread the message that they won't tolerate knife crime," he said.
"By working together we will make our streets and communities safer."