The concept of codependency and coaddiction has achieved a prominent place in the fields of substance abuse and sexual / behavioural addiction and indeed in the addiction literature. The manner in which definitions of co-dependency have become increasingly inclusive are probably related to continuing input from both self-help movement and from psychiatric perspectives. Coaddiction on the other hand is a term referred to by Patrick Carnes (2001) as the spouse, partner or family member of a sex addict. The purpose of this research is to review the constructs of codependency and coaddiction, discuss related issues to the validity of the constructs of codependency and coaddiction and to compare both the constructs, reviewing any possibility similarities and or differences between the two constructs. The possible aetiology to explain the phenomena of these constructs within the context of substance addiction, sexual addiction, and possible family of origin issues.