Interpersonal Therapy (IPT) is a therapy treatment for depression.  It differs from CBT in that the focus is on relationships with other people more than internal thoughts and feelings. 

 The idea behind IPT is that when we are feeling depressed it can affect our friendships and relationships and in turn difficulties in relationships can trigger depression.  The interpersonal therapist aims to help you identify how you are feeling and behaving in your relationships and develop more helpful ways of relating to others.