This dress will fit average fullness 18” doll such as American Girl and similar.
Yarn used here is a full bodied “baby” weight or light weight Sports yarn. I strongly recommend using cotton blend yarn and it can be steamed and it is still soft and it drapes well too.
The dress can be knitted either flat with back seam (as shown in photo) or in a round (adjustment is not included in the pattern).
Back has an opening and button fastening.
I used a variation on a “rick-rack” stitch here for vertical ribbing.