A number of ideas have been put forward to help understand the relationship between, on the one hand, individuals within a family (or the family as a whole) who are affected when a member of that family develops an addiction-type problem (with alcohol or other drugs or gambling), and on the other hand, that person in the family who has developed such a problem. This chapter outlines some of the main perspectives that have been developed, including genetic and biological perspectives, psychological perspectives (including psychodynamic, ‘co-dependency’, stress-coping and family systems) and sociological/political models (such as feminism and community psychology). It then examines the implications of these various conceptual models for theory, policy and practice, before concluding with a summary of the AFINet approach.