Based on Samantha's Birthday Party Dress for girls from American Girl (below). Unfortunately, they do not sell the girl-sized version any more, but you can find it on eBay.
The dress has large balloon sleeves trimmed in lace, a high collar, a 'pouter pigeon' style bodice (very popular in 1904), and full gathered skirt. It buttons up the back. The pinafore has horizontal tucks down the center, lace-trimmed bretelles, and a sash that ties in a big bow.
I preferred the design of the doll's dress rather than the girl's and so made my version based on that. The dress is made simply from a piece of pink-and-white striped cotton (thank you, Bethany!) and for the pinafore, a sheer voile curtain from the thrift store! I trimmed it all with lace from the stash.