I discuss theoretical models of individual development in a dyadic system and their importance for couple therapy. These models are based on early infant research about the dyadic system created between caregiver and child and include ideas about self-regulation and mutual regulation. These related and overlapping theories are also relevant to the use of couple therapy with partners who have histories of early trauma. Traumatized individuals tend to use avoidant, disorganized, or ambivalent strategies of stress regulation, as opposed to secure and responsive ones. These strategies cocreate problematic interactive patterns in their couple relationships. It is therefore important to establish a therapeutic atmosphere of empathy, responsiveness, and trust that facilitates the partners' capacity to change their interactive patterns. This therapeutic atmosphere serves as a model for the partners that aims to promote more secure attachment, understanding, and growth.