This sounds like a really hard one to deal with. Why not talk to her doctor and ask for some advise before any more time passes. I'm sure many people have had this problem and perhaps a bit of professional advise, sooner rather than later, can eleviate a potential ocb behavior. Who likes to go to public bathrooms? Not I. Certainly it happens to many of us, but this happening to her so early in her life sounds as it could become intertwined to maybe the beginning obsessive compulsive stuff. With her not wanting to use any b/r but one in your house, and now making a choice to leave a party because it isn't the "one" potty is potentially more than something odd. I'm sure she didn't want to leave her friends at this party, but the compulsion to go to her own potty was greater than enjoying herself, to me, raises a red flag. I'm in no way a professional, a grandmother in fact...and my 6 year old grandson entered 1st grade last year only to "hold it" until he gets home. Just a thought, maybe you could put some of her books or cherished babies etc., in the other bathrooms...there is this fine line, I've never fully understood, about the toilet training being part and their development in other area's of life. If you do get some kind of good advise from you doctor, please share it with me so I can pass it on to my grandson. Good luck M., this is just the beginning of many different approaches to problems in regards to child rearing, and from what I've heard, this is a very important one.