Nonsexual boundary crossings can enrich psychotherapy, serve the treatment plan, and strengthen the therapist–client working relationship. They also can undermine the therapy, disrupt the therapist–patient alliance, and cause harm to clients. Building on T. G. Gutheil and G. O. Gabbard's (1993) conceptualization of boundary crossings and boundary violations, this article discusses and illustrates grounding boundary decisions in a sound approach to ethics. We provides nine useful steps in deciding whether to cross a boundary, describe common cognitive errors in boundary decision making, and offer nine helpful steps to take when a boundary crossing has negative effects. © 2008 Wiley Periodicals, Inc. J Clin Psychol: In Session 64:1–15, 2008.