This thesis research examined the relationship between SWB and depression in the context of homeostasis theory. Results provide support for homeostasis as the SWB maintenance mechanism and strong support for conceptualising depression as a loss of SWB. Remarkable, results also indicate that some SWB measures outperform depression inventories in detecting depression. The portfolio uses attachment theory as a conceptual framework for understanding the contribution of attachment relationships to the development of borderline and antisocial personality pathology in children and adolescents. Four case studies are presented in illustration.