I say let her wear the suit! Women do wear pant suits, ya know, and at age 6 the cut isn't going to differentiate between a girl's figure and a boy's. Do you happen to own a nice pant suit yourself that you could wear that day? Or some nice slacks and a blouse? I'm planning on wearing linen slacks and a blouse to my 60th birthday party. I haven't been very specific as to attire in the invitations and decided that my bell-bottom linen slacks and a top would be drapy enough not to make any dress wearers uncomfortable and at the same time would keep company with any pants wearers amongst the women. Also, I happen to like them and like how they look on me. A friend of mine, when preparing for her dissertation defense, was instructed to wear "a tuxedo or the equivalent" (unisex instructions based on decades of almost only men taking PhDs). She went with the tux, a tight-waisted one that fit her figure. Very stylish! See? Even grown-up women wear pants at dress-up occasions sometimes.