As many other reviewers stated, this bra runs particularly small for the Jezebel brand.  Mostly in the cup, I would recommend definately sizing up cup-wise, but it wouldn't hurt to do the band as well.  I wear a 36D or 36DD depending on brand.  I've purchased other Jezebel bras in 36D and they've fit fine, but this one was particularly too small in the cup (sadly does not come in DD), and if I had a choice, I would have gone to 38 as well.