In a letter to Facebook CEO Mark Zuckerberg, Reps. Ed Markey (D-Mass.) and Joe Barton (R-Tex.), who co-chair the bipartisan Congressional Privacy Caucus, raised a number of questions about how children will be protected under the new scheme, including what data would be collected, what advertising would be targeted to children, and how the social networking site plans to get parental permission across multiple platforms.

Markey and Barton also questioned the social network's timing of the news, which came on the heels of a disappointing IPO and the need for the company to take advantage of an untapped market to prove its full revenue potential to investors.

"We believe strongly that children and their personal information should not be viewed as a commodity to be bought and sold to the highest bidder," the Congressional privacy duo said in a statement.