Microsoft Corp. and Yammer on Monday announced that they have entered into a definitive agreement under which Microsoft will acquire Yammer, a leading provider of enterprise social networks, for $1.2 billion in cash. Yammer will join the Microsoft Office division.

“The acquisition of Yammer underscores our commitment to deliver technology that businesses need and people love. Yammer adds a best-in-class enterprise social networking service to Microsoft’s growing portfolio of complementary cloud services,” said Steve Ballmer, chief executive officer of Microsoft.

The Yammer service allows employees to join a secure, private social network for free and then makes it easy for companies to convert a grassroots movement into companywide strategic initiative. Launched in 2008, Yammer now has more than 5 million corporate users, including employees at 85% of the Fortune 500.

Yammer will continue to develop its standalone service and maintain its commitment to simplicity, innovation and cross-platform experiences. Moving forward, Microsoft plans to accelerate Yammer’s adoption alongside complementary offerings from Microsoft SharePoint, Office 365, Microsoft Dynamics and Skype.

The acquisition is subject to customary closing conditions, including regulatory approval.

Tags: Microsfot, Yammer