This two hour presentation will present our evolving theoretical model, developed with a close group of colleagues, of lifespan self development and the key capacity for affect regulation. The model concerns the quality of attachment and the growth of different aspects of mentalization, and is rooted in theoretical, empirical and clinical work. Links with related concepts will be clarified. We will begin with the ways in which infants and children learn about the social and material world within relationships then focus on the development of a robust capacity for affect regulation, or the moderation of emotional states to within a range that allows creative relationships and learning. A clinical illustration will be given from adult psychotherapy and implications for practice will be discussed.