Cardiac disease is a major threat to the quality of life of both patients and families. Using King's definition of a social system, this article provides a general overview of the impact of cardiac disease on the family social system. Acute and chronic illness require emotional, cognitive, and materials support to prevent maladaptive coping by patients and family members. Techniques for family assessment are detailed. Specific interventions appropriate for acute, transitional, and rehabilitative care are provided. Implications for nursing practice and research that includes family members are given. © 1989 Aspen Publishers, Inc.