A personal boundary is a fundamental component of selfhood; it refers to the ability to define one's self as an independent individual deserving of fair, respectful, nonexploitive treatment that is informed by widely accepted standards of legal and human rights. Healthy selfhood brings with it the capacity to have well-defined demarcation points whether the issue being engaged is physical, sexual, financial, or property related or has to do with privacy and confidentiality. This entry discusses the nature of personal boundaries with particular attention to the therapeutic relationship, beginning with the clinical profile of individuals who have experienced trauma regarding boundary issues. The next section outlines the historical evolution of the concept of boundaries within the discipline of classical psychoanalysis, including the complex and fraught circumstances ...