Yes, you can definitely do that.? You can set it for "Not listed in the directory, private archives".? You'd want to make sure that all members must be approved to join.? If you set up a Group Guidelines notice, you'd also need to set that so only group members could see it.? You may need to go to some of the other sections of the Settings page to make sure nothing is set for public view, Calendar and Wiki come to mind.
Duane
Duane