Take your two front pieces and put them right sides together. Sew from waist down to crotch. Then do the same thing with the 2 back pieces. Now you should have a front and a back. Put them right sides together line up the crotch seams and sew your inseam. Then sew the side seams. Now all you need is the waist and hem.
Susan

There are lots of ways to do things and I do mine just the opposite. I sew a front and back together at both side seam and inseam. Then I leave one wrong side out (the outside one) and turn the other right side out and stuff it down into the one that is wrong side out. Shake it down and match up you raw edges and sew from the top, down through the crotch and up to the other top.

I do it pretty much the same way as soonergrandmom, except I sew the 2 inseams (L front & back, R front & back), then the crotch seam, then sew the side seams.

Donna

I have done them the way Donna and SoonerGM described too. I think I have the other way in grained in my brain from making so many pairs of pantaloons, LOL.
I'm pretty sure the PJ pattern instructs you to do them the way they did.
Susan