My best friend has twins and apparently potty training them is extra tough with twins because they sort of make a silent pact not to do it. She even has an older daughter who the twins look up to who was telling them about going on the potty and being big girls, but they still wouldn't do it. This will sound terrible, but she decided she had to break them. When they were three, she had put them in underwear but let them wear a diaper for nap time, and they had gotten to where they would hold it all day until nap when they got a diaper. So she knew they were ready to potty train physically, just not mentally. One day she gave them all the juice and soda and liquids they wanted that she never lets them have. They kept saying they were ready for nap hours before it was time. She'd say, it's not time yet, sweetie. Would you like to try to go potty? They'd say, no, so she'd say, ok, how about a drink of juice? Since they didn't get the correlation, they'd say yes. Finally one of them was in so much pain, my friend pleaded with her to sit on the potty. She did but still didn't want to go. My friend was desperate. She told her if she'd go, she would buy her the princess Barbie she'd been wanting. The other twin overheard the offer and asked if she could have it if she went. My friend said yes, and that twin said ok, and finally went on the potty. Hallelujah! The first twin was still hesitant, but my friend told her she was going to the store right then to get the Barbie so she would get her one, too, if she went potty. And she did. And once they went the first time, they never had a problem with it again. They were super easy to train. It was just getting them to start.