For my slim 12 year old, the dress fit very poorly. Waist too wide, arm holes too small and uncomfortable, neckline a bit too open. Very short! We ordered XL as per size guide.

This neckline dipped way too low on my slim 11yo. Not only could you see her undergarment, but the dress wouldn't meet our school's dress code of sitting at least as high as an imaginary line between armpits. Note, this was actually a SIZE DOWN (L) from what her height suggests she should be wearing (XL) and was still too loose in the neckline. It was also a little too wide on her for the style and looked like it would likely shrink too much in length after washing. We like the color and pattern, but don't recommend this dress to other girls with really slim builds (shoulders, waist).