This study examined how individuals do boundary work, the process of negotiating, setting, moving, and adjusting boundaries between work and life outside of work. In an inductive qualitative study of 70 attorneys in a large U.S. law firm, I found that boundary work cannot be fully understood unless we consider relationships within which it happens. Attorneys engaged in different types of boundary work in different types of relationships that activated either approach or avoidance motivation to pursue substantive (i.e., boundary-related) and relational goals. Boundary work led to measurable and predictable outcomes—success in boundary setting and impact on relationships—that depended on the nature of the relationships and the type of boundary work used. I propose a theoretical model of boundary work, a set of propositions, and discuss theoretical and practical importance of examining boundary work in the context of interpersonal relationships.