Over the past decade there has been an explosion of interest in clinical applications of attachment theory. In this lecture, we describe John Bowlby’s model of therapeutic change, the therapeutic relationship, and the therapist’s role in emotional healing. We then review empirical evidence for three key propositions in Bowlby’s model. First, a client’s sense of security during therapy is crucial for facilitating therapeutic work. Second, a therapist’s own sense of security contributes to positive therapeutic outcomes. Third, attachment insecurities can be effectively reduced in therapy, and movement toward greater attachment security is central to achieving favorable therapeutic outcomes. Finally, we will apply the theory and the research it has generated to couple and family therapy.