Learning Objectives By the end of this section, you will be able to: Define interpersonal theories and therapies: Sullivan, Erikson Identify nursing application of interpersonal theories and therapies: Peplau   Interpersonal theory, first described by Harry Stack Sullivan (1892–1949), holds that human behaviors can be explained through relationships with others. Influences from these relationships shape … Continue reading 2.3 Interpersonal Theories and Therapies