I have one twin potty learned and the other is as stubborn as a mule on this subject!! What I did was introduce the potty chair and the seat that goes on the toilet. I let them mess around and pretend to potty with their clothes on. Older brother joked around and pretended to sit and potty too and the boys thought it was funny and mimicked him. Shortly there after, after every diaper change, I would have them sit on the potty and try to pee. After a few times, they were both successful with going potty after diaper changes. Then I let them sit on the toilet on the seat insert. That worked great. They both wanted to climb up and go potty! That was in November this past year. They were 2yrs 10mos old. One twin, J, started wearing underwear cause he thought it was cool. I figured a few accidents wasn't going to hurt him or I any. I just reminded him every half hour or so to use the potty. Then one day, he came to me and said "I go potty now" and that was it. He pretty much potty trained himself!! He even started going poopy while on the potty. At parents day out (one day a week), the teacher was letting him stay in underwear during nap and he stayed dry so I started that at home. He has had a few accidents at nap but very few. Now they are almost 3 1/2yrs old. Like I said, one is potty trained, the other, not so much! I am working on it but he refuses, ie: starts crying, when I mention wearing underwear. Older brother wasn't trained till one month shy of 4yrs old so I am guessing R, is taking after him. I will keep gently trying and hoping maybe at the end of the summer he is trained. I guess for both of us, we just keep trying! Take one day at a time. Maybe focus on one at a time and maybe the other will follow in her sisters footsteps.