This article reviews the family constellation of patients with obsessive compulsive disorder (OCD), the presence of OCD symptoms among family members, and familial aspects including parental attachment, expressed emotion (EE), and family accommodation. Some evidence supports a negative effect of hostility, emotional over-involvement, and criticism perceived by the patient on behavioral treatment outcome. However, actual criticism observed by the relative during an interview was associated with more benefit from therapy. Family accommodation predicted poorer family functioning and more severe OCD symptoms after behavioral treatment. A review of the limited treatment literature indicates no actual tests of the effects of psycho-educational and supportive treatments, although several reports suggest they are useful for families and patients. Including relatives in treatment has proved beneficial in some studies, especially with children, but not in others. Multiple family groups that focus on behavioral contracting for exposure and stopping rituals may be a promising intervention. Likewise, efforts to reduce family accommodation in the context of behavioral treatment have proved useful. Additional research on the content, process and effects of family interventions for OCD is much needed.