How effective is mindfulness for anxiety? how does it compare to cbt?

Moderately effective: Research studies have shown clear benefits of mindfulness meditation for anxiety though most of the studies were not on people with severe anxiety; a review of 47 studies showed moderate evidence of improvement- see http://hub.Jhu.Edu/2014/01/08/meditate-to-reduce-depression research also shows cbt is helpful but no studies have compared them. I think it is reasonable to try both approaches.