Here is a page of pattern pieces to make a dress in long or short length for an 18 inch fabric or vinyl doll, such as Gotz, or American Girl.
Pattern pieces for dresses that will fit American Girl, other historical dolls, Corolle Dolls, Gotz Precious Day Girl Dolls and similar size dolls. - American Girl and Similar Dolls - Dress Pattern - Doll Making is a personally written site at BellaOnline
Sew Dolls and Costumes: Pattern Pieces for 18 Inch Doll Dresses by judierob
Free Printable Doll Clothes Patterns | Free fashion patterns for American Girl Dolls