What should I wear to an open interview?

Dress like you would for a typical first-round one-on-one interview. Business casual usually works for open interviews, but when you research the company, try to see what kind of culture they have. If they're in a professional industry like finance, you should air on the side of dressing more formally.

For other jobs in retail or tech start-ups, you may be able to get away with a smart casual look. If you don't come across any clues about the company culture as you research, it's better to dress more formally so the employer knows you take the opportunity seriously.