The impact of chronic illnesses upon children and their families can range from minimal disruptions to severe distress and functional limitations. Advances in medical care and technology have increased the lifespan of children with chronic illness as well as decreased the frequency of readily observable disease impacts on this population. To enhance our understanding of the more subtle, but equally important, impacts of pediatric chronic illnesses, researchers have expanded the domains assessed to include measurement of child adjustment and family functioning. Understanding the nature and development of the deficits in family functioning is key to the formulation of interventions designed minimize the impact of childhood chronic illness on family functioning. Additionally, exploring the role of chronic illness on family functioning will clarify the role of the mechanisms that lead to shifts in family functioning.