All human beings have defences some of which are unconscious, that is, reactions that for the most part lie beyond our immediate awareness and control. The purpose of this paper is to introduce the important role that defences play in social work and to identify the knowledge and skills that are needed when working with anxieties that lead to defensive behaviour. The paper is in two parts. The first provides a theoretical account of what is meant by the term defences, anxiety, resistance and related concepts, and then goes on to describe a number of key defences that are regularly encountered in social work, and in other related fields of practice. A second section looks at how we can work creatively with unconscious, defensive reactions and resistances, particularly the importance of containing anxiety. It describes how transference, counter-transference and projective identification can aid our understanding and help to illuminate the feelings, fears and fantasies that are evident in our work.