In this study, we investigate information privacy control within groups on social media sites. Privacy control is redefined to be not a concern but the actual control mechanism over the collected information by social media users. A research model is developed that considers the relationship between group privacy control and personal information disclosure behavior. We propose that average privacy control within a group has a curvilinear relationship with personal information disclosure behavior. We also propose that the variance of privacy control within a group weakens the relationship between average group privacy control and information disclosure. Our model will be tested by a laboratory experiment with a 2 (average privacy control within a group: low vs. high) x 2 (variance of privacy control within a group: low vs. high) factorial design.