Since reading this forum helped me plan my DD's 16th bday party, I thought I would post my top tips for holding a (relatively) successful party for teenagers, with alcohol:
The 3 most critical things:
-Having our daughter as invested as we were to not having drunk kids at her party was key. She sent links to a private FB page with the details of the party and a request NOT to bring any alcohol. A week or so before, a few kids mentioned that they were going to bring some, so she cut their link to the page and told them not to come. They didn't.
-Don't go it alone. It would have been very difficult for my husband and I to manage 35-40 kids on our own. Luckily, we had the dad of one of the kids helping us. You need to recruit at least one other parent, preferably more, preferably big, tall people. Worst case, hire a bouncer or security guard.
-Do not let people leave the party and come back. We stationed an adult just outside to keep the kids inside and supervise the ones who went out for a smoke. Kids who leave are likely to smoke pot or drink alcohol they may have stored outside - then return and cause trouble. If you let people drift away unsupervised, you lose control
-we rented a village hall rather than using our own house. Next time, I'd consider organizing a cleaner to come tidy up afterwards rather than us having to do it.
-we provided lots of food - hot food moved better than cold
-we provided 20 75-cl bottles of French cider (5.5% and 3.5% alcohol). When it was gone, it was gone.
-we asked everyone to write down their name and their parents' phone number as soon as they arrived.
-monitor all entry ways to the party and take all coats and bags. No exceptions. Even so, we didn't realize there was another entry and some of the bags were accessible until it was too late...
While I am not going to be doing this again anytime soon (sorry, younger son!), we feel it went as well as can be expected. A few girls got drunk and two kids got sick outside the hall. We confiscated a bottle of vodka in the first hour from one boy and broke up a pot party on our village green. About 20 kids spent the night at our house and we had to take another bottle of vodka, some cans of cider and some alcopops off them - even though we clearly said NO ALCOHOL IN THE HOUSE. My daughter was in tears, she was so disappointed in some of her friends. A few crap kids can spoil the whole party.
On the positive side: All the kids were polite, even the ones we had to reprimand for bringing vodka, and nearly all of them remained pretty sober throughout. We were relieved that no one threw up inside the house, no one got falling-down drunk or seriously ill, the police weren't called and everyone seemed to have a good time. It was over at 11.15 pm. The 20 or so kids who spent the night at our house all slept in one big room and used one bathroom, which limits the mess. They didn't sleep much but they were well-behaved. We gave them a bunch of croissants, tea and juice then next day and they were all gone by 10.30 am.