First I have to let you know that I generally don't wear slides.  I have narrow feet and slides don't stay on well.  I've gotten more interested in them since I've seen more of them in narrow sizing and I have found some good ones that work for me.  I usually wear a 9 narrow shoe and an 8 1/2 medium in sandals.  I ordered an 8 1/2 N wanting to make sure they weren't too loose.  I got these to wear to a more casual wedding but I'm sending them back....one of the shoes was too wide and the other was very snug.  That said, they are attractive shoes and I like the heel height.  I'll keep looking....