This chapter covers the vast terrain of ethically informed boundaries in certain kinds of professional relationships. When discussing the importance of professional boundaries in mental health work, most people think fi rst of relationships between psychotherapists and clients. However, similar boundary considerations are relevant for professor-student relationships ( Biaggio, Paget, & Chenoweth, 1997 ;Lamb, Catanzaro, & Moorman, 2004 ), supervisorsupervisee relationships ( Gottlieb, Robinson, & Younggren, 2007 ), consultant-consultee relationships ( Koocher, 2009 ), and researcher-participant relationships ( Haverkamp, 2005 ). Although different dynamics are at play, the relationships psychologists have with each other, with other professionals, and with the general public have boundaries that warrant ethical consideration as well ( Rubin, 2000 ). To some extent, the contents of this chapter will apply to all of the professionals, but with more attention devoted to the therapistclient relationship. Separate chapters are included in this handbook on emotional, romantic, and sexualized boundaries (Chapter 11 of this volume); academic excellence (Volume 2, Chapter 12, this handbook); supervision (Volume 2, Chapter 13, this handbook); and research (Volume 2, Chapter 16, this handbook).In my rural state, there is a folk saying: Good fences make good neighbors. In this succinct bit of folk wisdom, the existence of good fences creates and defi nes the relationship. This is a chapter about professional boundaries, which, like good fences, are essential for good professional relationships. Boundaries create and defi ne the professional psychotherapy relationship. When boundaries are clearly articulated, fully explained, and wisely and compassionately tended, the professional relationship stands a strong chance of being healthy and helpful.The folk saying implies that the neighbors are of equal standing. However, we need to consider an added dimension to our discussion of boundaries in the context of a professional relationship: The parties in a professional relationship are not on equal footing. In professional helping relationships, an inherent power differential brings a great deal of moral weight to bear on the professional. Becoming a professional means fi nding ways to accept and handle the power inherent in the role. In The Social Origins of Professional Sovereignty , Starr (1982) wrote, Power, at the most rudimentary personal level, originates in dependence, and the power of the professionals primarily originates in dependence upon their knowledge and competence. In some cases, this dependence may be entirely subjective, but no matter: Psychological dependence is as real in its consequences as any other kind. Indeed, what makes dependence on the professions so distinctive today is that their interpretations often govern our understanding of the world and our own experience. To most of us, this power seems legitimate: When professionals claim to be authoritative about the nature of reality, whether it is the struc...