Making the transition from baby in diapers to big kid underwear is an important stage in child's development and Pull-Ups can help. In our house we are a little late to the party because Peanuts has an Autism diagnosis so there are many things that we are *just* starting to attempt more of (like speech and eating more than just pasta and fruit every day ;) )
We started a few weeks ago with underwear, figuring the Christmas break from school would be a good time to focus on going to the potty many times during the day without any interruptions and so far.... things are going much better than anticipated. We are still having poop accidents so if he is having a particularly active bowel day we keep him in his Pull Ups which keep things contained just as well as a regular diaper and the velcro sides make for easy removal but they also slide on and off really easily for all the other potty trips just like regular underwear! I received a pack of regular Pull Ups to try from Influenster, which work just fine for us, there is a version of their product out there that have "Cool Alert" but that did not seem to be enough of a change for my little guy to notice, we had to go the slightly more laundry-intensive wet underwear route. We also use pull ups for bed time still in our house until I can be sure he isn't going in the middle of the night, we bed share so there would be 3 of us trying to sleep in a wet spot if that happened :\
You can buy Pull Ups in both girl and boy prints, and they come in 3 size ranges : 2T-3T, 3T-4T and 4T-5T .
There are also many opportunities to buy this product on sale with additional money taken off via coupons in both Canada and The US, which is a plus because it doesn't matter who you are, there is a good chance you are going to be using this type of product for a few weeks.