This chapter reviews theories that speculate how love and our earliest relationships impact health and well-being. From the theories of attachment and bonding described by Anna Freud, Melanie Klein, John Bowlby, Harry Harlow, Mary Ainsworth, Mary Main, and T. Barry Brazelton, to the more recent theories of developmental neuroscience described by Allen Schore, Daniel Seigel, and Bruce Perry, the chapter explores why that first relationship is essential in every aspect of healthy development. Even though bonding and attachment have been explored in the literature on human development and psychotherapy for over 100 years, it is only in the last 2 decades that these theories have been considered integral aspects of psychotherapy. The clinical relationship and therapeutic process can address early childhood relationship damage. The chapter concludes with a brief discussion of how the therapeutic relationship impacts the efficacy of child psychotherapy.