I believe that as a general matter, PA does not impose "social host" liabiltiy on people for serving alcohal to guests aged 21 or over, though it does allow liability against "dram shops"--anyone with a liquor license. What you describe would likely not fall under the dram shop liabilty provision, so you should most likely not face liability for any drunk adult guests. You can also create liability waivers which will help insulate you from liability from ordinary carelessness on your part--though you can't insulate yourself from liability if you are reckless or grossly negligent (more than normally careless), in the event such liability could be asserted against you in the first place. It would be a good idea to draft and have people sign such waviers; it would also be a good idea to exercise basic common sense and care, like cutting off anyone who is imbibing too much or seems drunk, calling cabs if necesary, etc. Again, while it looks like you'd not face liability in any event, it's a good idea to take reasonable precautions.Where you face the greatest exposure is if any of your guest are under 21--if they are, and you were lax in any way in checking IDs, you could then face liability.