A long dress for Barbie. Dress in the photo has been modified to be shorter.

Look for pattern by number at http://www.stickatillbarbie.se.
The website is in English & Swedish, but patterns are available in several languages.

On the website you’ll find the patterns listed on the left, by number, grouped on pages.
Accessories like hats, scarves or bags are listed in the accessory section, below in the left column.
Click on numbers to open a page, look for the numbered image, then for the link to the desired language below it (clicking on the image will only enlarge it).

This pattern comes in a .doc file, except for Russian version that links to another website.

Specific yarn is suggested in some languages only, while others call for generic cotton yarn.
Gauge is not given in the pattern but you can find it in the yarn section of the site.

Bodice is worked flat, then skirt is worked in the round.
Pattern doesn’t tell whether the top part has to be sewn or if you have to add some kind of fastening.

Boa: pattern A19