Depression is a very common disorder that is frequently associated with considerable morbidity and a much increased rate of mortality. It presents in various ways depending on a person's age, sex, and ethnic and cultural background. Recent advances have indicated that it is not a single condition. Not only do unipolar and bipolar depression require different management but the recognition of the importance of inflammation in cases of depression that are resistant to anti¬depressant medication opens up a whole new area of potential intervention. This focus issue of Cutting Edge Psychiatry in Practice draws together a wide variety of papers from international and UK authors. The topics cover a very broad range, from epidemiology, genetics and neuroim¬aging to pharmacological and non-pharmacological management. I have been pleased to be the consulting editor for this issue. I hope that such an interesting collection of papers will inspire professionals to build on the knowledge that has already been established with even greater re¬solve and to carry out further research to improve the management of this important condition.