no matter what the size, this dress runs small.  my daughter is almost 4 years old, about 43 inches tall & weighs ~35 pounds.  she has this dress in 3T-4T (which is more like 2T), the size "small" which is size 4-6 (which fits her normal/slim frame perfectly but doesn't leave room for any significant clothes on under the dress / along waist chest area), and also size "medium" which is size 8-10 (which fits her frame loosely and seems just a little bit too big, but will allow for layers of clothing underneath so she can wear it trick-or-treating in the chilly ohio halloween).  the frilly part that peeks out of the bottom is pretty, but VERY scratchy, so something needs to be worn underneath.  the sequins are nice, especially when out in sunlight there's an iridescent shimmer to them; but they do come off sometimes (but not too easily) and the sequins are like stickers.  bought toto from a local party store, and red shoes from amazon primigi brand (very nice, but size runs very big).