Examined cancer patients' desire for social support from family, friends, and health professionals upon whom they most depended for support. Before a single interaction with each of these sources, nonhospitalized adult cancer patients (N = 64) completed a questionnaire indicating their desire for support from the source on 11 functional components. Results indicated that emotional and instrumental functions of support were distinct and required separate examination. Distinctiveness of primary sources was manifest by patients' overall preference for tangible aid from family, modeling from friends who had cancer, and open communication and clarification from health professionals. Family and friends were equally preferred sources for dealing with affective reactions to the stressfulness of cancer. All three sources were similarly desired for self-esteem enhancement and for relief from decision-making and problem-solving responsibilities. Finally, patients' perceived prognosis but not the objective severity of their illness was associated with a heightened desire for support, especially for instrumental support functions.