BACKGROUND: Understanding the challenges faced by family members involved in decisions about the use of life-sustaining treatment for incompetent patients in the ICU is necessary for developing empirically based supportive interventions. OBJECTIVES: To describe and explain the experiences of family members who were involved in decisions on behalf of their loved ones in order to promote understanding of such experiences and to suggest areas for effective, supportive intervention. METHODS: The grounded-theory method of qualitative research was used. Data collection involved semistructured interviews of 17 persons who had been involved in decisions about the use of life-sustaining treatment for a family member in the ICU. RESULTS: Family members discussed the need to arrive at a judgment of the patient's condition and to work with caregivers to have the family member's decision about life-sustaining treatment enacted. Data analysis suggests that clinicians can best support family members by helping the members arrive at a judgment about the patient's condition and treatment desires and by connecting with the family members to ensure that treatment goals are mutual. Supporting family members in this way helps them accept and go on in a positive way after the experience. CONCLUSIONS: Family members of patients in the ICU are willing and able to take responsibility for decisions about the use of life-sustaining treatment for their loved ones. The long-term acceptance of the experience and the decisions made depends greatly on the interactions between the family member who makes the decision and nurses and physicians in the clinical setting.