Depending on how exclusive you want your Facebook group to be, you can configure its privacy level from Open to Secret. A secret Facebook group provides the most privacy, with Facebook mechanically hiding its very existence from the public with the tweak of a setting. In maintaining a group’s secrecy, though, automated concealment is only half the battle. The other half is human nature, which you can vigilantly control as a Facebook group administrator.

Privacy Setting

To enjoy the highest level of group concealment, set your Facebook group’s privacy level to Secret. Unlike the Open and Closed privacy options -- which openly broadcast a group’s name and members -- the Secret option keeps your Facebook group's name, members and posts publicly invisible, unsearchable and un-shareable. You can activate the Secret setting at a group’s inception or upgrade an existing group that you administer to Secret status. For a new group, select the “Secret” privacy option after clicking “Create Group” on the left sidebar of your Facebook home screen. On a pre-existing group, click the gear icon, then click “Edit Group Settings” and activate the “Secret” privacy radio button. Click "Save."

Group Guidelines

As a Facebook group administrator, you should establish guidelines that clarify your group’s purpose, set members’ expectations and define what constitutes acceptable and unacceptable conduct. On a Secret group, these guidelines are also a good place to stress and remind all members to maintain secrecy. Explicitly describe what may or may not be shared beyond the group’s confines and what penalties would be meted out to those who violate your code of secrecy. You can prominently display your secrecy mandate and guidelines in the group’s About section; simply key them in to the Description box within its settings.

Membership Control

Membership in a secret Facebook group is strictly by invitation only, with its first members being invited by you over Facebook or via email. Afterwards, members may invite others to participate in your clandestine group. While you might be able to vouch for the trustworthiness of your group’s initial members, their honesty and good judgment are not necessarily shared by their friends or friends of friends. To ensure optimal secrecy, continue to control who becomes a member of your group. By default, all members may invite and approve other members to the group. To change this, choose “Any member can add members, but an admin must approve them” in your group's settings.

Group Expulsion

Within any community -- including your secret Facebook group -- not everyone plays nice all the time. For the most egregious infractions, you can expel offending members. Simply click the members link next to "About" on your Facebook group page, then click the gear icon below an offensive member’s name and “Remove from Group.” Henceforth, the banned member won't be able to find your group, view its contents or rejoin the group except with your approval as administrator. However, don’t reinstate any member who’s intentionally caused privacy leaks from within your secret Facebook group.