The concept of condependency has achieved a prominent place in the psychiatric, psychological, and addiction literature in a remarkably short period of time. Although the term was first developed in the substance abuse treatment arena, specifically referring to the wives of men who abuse alcohol, codependency has more recently been used almost generically to describe a dysfunctional style of relating to others (Irwin, 1995). The manner in which definitions of codependency have become increasingly inclusive are probably related to continuing input from the both the fashionable self-help movement and from some psychiatric perspectives. The purpose of this article is to review proposed definitions of codependency, discuss issues related to the validity of the codependency construct, and summarize efforts aimed at producing instruments to measure codependency. Additionally, I will address implications of this concept as related to psychiatric nursing education, practice, and research.