My dd#1, 13yo, has just started to hang out 'unsupervised' with kids after school. The JR High is fairly close to downtown and the kids want to go there after school. She is to tell us who she will be hanging out with and then they have to come into dh store (coffee shop) to meet him so he knows who she is with. This has worked so far. dd is very responsible about doing this and honest. She has just started doing this, (the past few months) and it has been working well so far. dh employees also keep an eye on her which is kinda cute (Huge windows in corner shop).
As a family, we talk about drugs and sex quite a bit. It appears more than her friends' families. We have open communication and she talks freely with us about the social things going on within her group.
We trust her and we believe that she is making good decisions when 'unsupervised'.