Interesting that all the advice in this thread seems to focus on male attire for business casual:Seems the consensus for a guy is around a dark suit (black, navy, charcoal?), black shoes and socks, pale shirt. Have a tie to hand that goes with the shirt. You can keep this in your pocket while you scope out the rest of the attendees and retire to a quite bathroom to put it on should the need arise. Of course, you can also ditch the suit jacket over the back of a chair. So you wind up with, effectively, slacks and an open shirt.If our original poster is female, I'd go with much the same advice. Skirt and matching jacket in dark tones or perhaps a dark trouser suit. If a skirt, on or just above the knee is good. Fitting, shaped, but not tight. A pale blouse, buttoned in front, and not open enough to display all your wares. Also ensure the blouse is not transparent and be careful to wear appropriately coloured underwear to cater. Minimal jewelry. Small earings, studs or small hoops, not dangling. Perhaps a slim chain and pendant for the neck. Dark stockings or tights. Dark shoes with a small heel, but that's really up to the individual need. No toe-peepers.Overall, the idea is to be comfortable in your dress. Don't wear something just for the occasion that you wouldn't be comfortable wearing in "downtime" in the office. Comfort in your surroundings, that is, as well as comfortable for your body and the conditions.Remember too that this is for a Big 4 assessment, so take a clue there. This is not a media gig, so turning up in a caftan probably won't cut it.Hope that makes sense.