The myYearbook site is popular among high school-aged users, who use it to chat, play games and buy and sell items with virtual money.
Quepasa, whose own networking site is aimed at Latinos and also features online games, said it would pay $18 million in cash and $82 million in stock for myYearbook. The deal requires approval from shareholders, which is expected.
Shares of Quepasa were down more than 7 percent to $9.22 in trading Wednesday, a day after the deal was announced.
"With this merger, we intend to create nothing less than the public market leader in social discovery," Quepasa Chief Executive John Abbott said in a statement. "Combination with myYearbook nearly doubles the size of Quepasa's existing user base while positioning the new company for significantly higher growth in mobile and social games, advertising, and virtual currency."
He said the staff behind myYearbook was product-oriented and ready to develop new products that will feed demand for converging social networking on mobile devices.
Social networks have become a thriving force online with the growth of Facebook and the recent addition of Google Plus.
Combined, myYearbook and Quepasa.com -- a social network with multimedia content in English, Spanish and Portuguese -- will have approximately 70 million users.
"Meeting new people is now -- and has always been -- one of the Internet's core activities," said Geoff Cook, David and Catherine's older brother. "This combination creates the scale needed to build the No. 1 player in social discovery."
