Yes you have to sign a waiver. Pretty much like if you walk through the gates of an amusement park, you are liable. There is ALWAYS at least 1 attendant to ensure everyone is following rules in addition to only allowing so many in the rooms to bounce. The price is very reasonable at about $8 per child to bounce for 2 hours. Yes the birthday parties are a little pricey, but add up how much you spend for food, drinks, and party favors to do this on your own. PLUS all of your time and energy to clean your house before and after the party and to set up everything. BounceU is very attractive in this manner, you show up 15 minutes before your party starts. After that every thing is done by the party hosts. AMAZING!