How do I require posts to be reviewed before publishing?

I plan to manage a blog with many contributors. I’d like the contributors to be able to log in and compose a post on WordPress, but I want to ensure that I am able to review each of the posts before I publish them.

I’m an Administrator of the site; all the contributors are Authors.

As far as I can tell, as authors they have the ability to *choose* whether their posts are published immediately or “pending review.” I want to take this choice away from them and force their posts to be saved as “pending review.” Is there any way to do this?