Well Is there any reason you have to follow the pattern instructions exactly. It's very hard to make 2 exactly the same if you hem them first. This seems like a odd set of instructions, the hem should always be last.

I've sewn lots of curtains and I've never used a pattern. The way I would do it is--

hem the sides of both the lining and curtain.
Put them together and sew the rod pocket.
Hang the curtains and pin the hems of both the lining and curtains and then sew.

Their way of sewing the hem first and then the side seams could cause the sides to pull up--my way keeps them flat

OilPainter,
Thanks for your reply. I am going to try your way later today. Here is the pattern I'm using from Simplicity Home Decorating book. I am a novice sewer, and felt that I would be better off following directions, instead of trying to wing it.

Step 1: Cut and piece the curtains. Using the cutting width and cutting length as your dimensions, cut the fabric for the curtain. If necessary, piece the panels, using 1/2″ seams.

Step 2: Hem the lower edge.

* After the panels are joined together, lay the fabric wrong side up on a large, flat surface. Press the lower edge up 4″, then 4″ again to form a double hem.

* At the location of the piecing seam, hand-tack a drapery weight to the inner hem allowance, 1/2″ from the hemline.

* Topstitch or, for a custom look, hand-sew or machine-blindstitch the hem in place.

Step 3: Press the sides.

* Press the sides in 1 1/4″, then 1 1/4″ again to form the double hem.

* At each bottom corner, hand-tack a drapery weight to the inner hem allowance, 1/2″ from the side hemline and 1/2″ from the bottom hemline.

* Do not stitch the side hems.

Step 4: Prepare the header.

* Measure up from the bottom hem and mark a distance equal to the cutting legth, minus the 8″ that became the bottom hem. Trim off the excesss fabric.

* Press the upper edge down a distance equal to the header depth and the rod pocket depth. Fold down again the same amount, forming a double hem; press again.

Step 5: Cut, piece and hem the lining.

* To determine the cutting legth of the lining, add the finished legth of the curtain plus the header depth plus 6″.

* To determine the cutting width of the lining, add the cutting width of the curtain plus 2 1/2″.

* Cut the fabric for the lining. If necesssary, piece the panels, using 1/2″ seam allowance.

* Press the lower edge of the lining up 3″, then 3″ again to form a double hem; stitch.

Step 6: Attach the lining.

* Place the curtain, wrong side up, on your work surface. Place the lining, right side up, over the curtain, so that the bottom of the lining is 1″ above the bottom of the curtain. Offset the lining slightly so any piecing seams in the lining and curtain are parallel and a scant 1/2″ apart. This will eliminate bulk in the header. Pin the hem allowances together at the bottom.

* Working from center to side, and bottom to top, smooth, press and pin the lining to the curtain.

* When you reach the top of the curtain, trimg the lining so it corresponds to the top of the header. Lift up the double hem and tuck the lining under it; pin.

* As you reach each side hem, unpin the hem, open it out and trim the lining to correspond to the inner foldline. Fold the side hems back over the lining; repin.

* When you get to the top, unpin the header area just enough to allow you to finish trimming and securing the lining under the side hems.

* Topstitch or hand-sew the side hems to secure the side hems to the lining. Then repin the header area.

Step 7: Finish the header and rod pocket.

* Edgestitch along the lower edge of the header area, through the curtain and the lining.

* Measure down from the top of the curtain a distance equal to the header. Machine-stitch, creating the header and rod pocket.