In graduate school, my policy on Facebook friend requests from students was that I would only accept them as friends after the semester was over. Since the likelihood of them having another class with me was very low I didn’t worry about them seeing ridiculous pictures of me and subsequently losing all respect for my authority in the classroom. When I started teaching at my current position, where the likelihood of interacting with the same students in multiple semesters is much greater, I changed my policy to reflect this by telling students that I would only accept their friend requests after they graduate.
Recent efforts to keep track of alumni, combined with Facebook’s movement of group management to a more convenient location (thanks Google+!), have led me to change my policy again. It turns out that students are more likely to send friend requests when they are in your classes than when they are not. This makes trying to build an online community of departmental alumni difficult after the fact. My new policy is to accept current students as friends while placing severe restrictions on the parts of my profile they can access. Students don’t see the pictures from my night at the bar with grad school friends, but they can see my status update about a recent sociologically-relevant headline.
Since I have only recently changed my policy and I am not advertising this change to students, I can’t evaluate the success of this change yet. The potential downside is that students may not control what their professors can and cannot see, so I’ll have to be careful to keep their photos of drunken nights and their ability to write and participate in class separate when grading.