These are great boots for toddlers- they are very lightweight, MUCH more so than typical rain boots so they are easy to walk in. They are great for mud, dirt, and rain but actually my toddler enjoys wearing them all the time because she can put them on and off herself. You can hose them off inside and out and they'll dry in about a minute because of the material they're made of. As far as sizing- they seem to run true to size and are fairly wide like all Crocs. My toddler has a very narrow, size 5 foot but the smallest size I could order was a 6/7 and I was worried they'd be too big, but it doesn't seem to bother her and she can easily run around in them.

*Update*
We have had these boots for over a year now. They have proven to be my toddler's favorite shoes. She wears them more than all her other shoes because they are so comfy and easy to get on. Very cute, very sturdy, clean up beautifully. The puppy got hold of them one day so they are peppered with tiny teeth marks now, but still going strong. Excellent purchase.