Attachment theory is often reduced to labels people use to explain their dating lives, but its clinical origins are considerably richer. Secure, anxious, and avoidant patterns describe different ways people organize themselves around closeness, separation, dependency, and the possibility of rejection. In psychotherapy, these patterns may emerge not only in stories about relationships but in the patient’s relationship with the therapist. An unanswered question, a therapeutic silence, a vacation, or even the end of a session can acquire very different meanings depending upon the patient’s expectations of others. Understanding attachment therefore gives clinicians a way of thinking about what happens between two people when one person begins to matter to the other.