The whole matter of changing pattern sizes is complicated but I do it and here's what works for me. 1. The body shape has to be the same. If the pattern is for a slender doll and you want to sew for an AG, you would be better off to find another pattern. 2. I use Julie Mueller's guidelines. She has written a great book "101 Bodice Designs." Her website is http://members.aol.com/anmueller/sew/sewing.html A pattern for a 16" doll enlarged to 113% should fit an 18" doll of the same body type. You will likely have to make adjustments, however. 3. Take off the seam allowance before enlarging/reducing. Otherwise the 1/4" seam allowance will also be changed. This step is crucial. I speak from experience. 4. Draw the 1/4" seam allowance back onto your new pattern. 5. Trace the pattern on paper towells, do-sew or muslin then use tape or pins to fit it to your doll and make the necessary adjustments before cutting out your fabric. The whole process takes a bit of time but if you really love a patterns and nothing else will do, enough patience will probably get you the look you want. I'm sure other people have better methods and I'm dying to hear. Good luck, Kathie