Every so often, because of trim or shaping, a sleeve should be shortened from the top. The method I use when shortening a sleeve this way is as follows:

First you must know how much shorter each sleeve needs to be. Pin a horizontal tuck (or pinch) from each sleeve, at the place it is easiest to pin. That is usually somewhere in the top half of the sleeve.
Mark the center of the sleeve cap with a pin or thread. Bring the line down to the “new top of the sleeve. Also mark any pleats that shape the sleeve cap.
Remove the sleeve carefully from the armscye.
Take out any gathering stitches so you can lightly press the sleeve cap flat. Don’t take the sleeve apart.
Measure, from the top edge of the sleeve, down as much as you figured the sleeve needs to be shortened. If shortening the sleeve 2″, measure around the entire top only 1 ¾”. This gives ¼” for any adjustment.
You can baste around the sleeve top at the new stitching line to hold multiple layers together, or just to mark the stitch line. Cut free hand or mark the cutting line first with pins. Mark the cutting line first to avoid any mistake.
If the sleeve had pleats or tucks for shaping over the cap, you have marked those lines in Step 2. Now retuck, using the lines as guides. Sew a double line of gathering stitches, just as you would in a new sleeve. (The shortened sleeve may lose a tiny bit of fullness, but that will be no problem.)
You are ready to pin the shortened sleeve into the armscye. Match the underarm seams, and the shoulder seam to the sleeve cap center that you marked in Step 2.
Pin the sleeve into the armscye about half way to the top on both front and back.
Now adjust the gathering stitches so the sleeve fits into the shoulder area of the armscye. Pin together, and see if you like the way it looks. (If you prefer, baste the sleeve in after you pin it in.)
When you like the way it fits the armhole, machine sew the “new” sleeve in, refinish the edges, press and do the other sleeve in the same way.
May Shaw is a writer for Hemming away – a newsletter for Wild Women Who Sew. For more articles like these subscribe to Hemming away. Order a subscription online at the website: http://www.hemmingaway.com

Check out The Sew Wild Club – it’s FREE! May Shaw is a professional seamstress specializing in bridal and special occasion sewing.
By May Shaw