Once again, we will refer to the trusted source on all-things-etiquette: Emily Post. Here’s what her site recommends:
Casual Dressy (for Women):
- skirt and dressy top
- dressy pants outfit
- nice jeans and dressy top
These first few categories (variations on casual) should be pretty easy, and relatively intuitive. Really, if you just bear in mind that just because it’s a casual (or dressy casual or business casual) event, it does not mean it’s pajama day. Or even Hawaiian shirt day. And you should probably think flats instead of flip flops.
On the flip side: Please don’t show up for a casual event in formal (or even semi-formal) attire. You really want to avoid out-dressing the hostess and/or guest of honor. The dress code is there for a reason. Respect it!