Residential instability is relatively common among low-income families and is associated with a host of negative outcomes, especially for children and adolescents. Psychiatric nurses, especially those in the advanced practice role, observe the consequences of residential instability within the clinical setting. Yet, to-date, the concept is somewhat vague and its essential meaning and definition remain unclear. The aim of this paper is to develop a definition of residential instability using Wilson's method of concept analysis. An overview of historical perspectives is included. The paper concludes with recommendations for future research and application within clinical practice.