When life crises occur, significant others are thought to help alleviate distress and resolve practical problems. Yet life crises may overwhelm significant others, eroding their ability to provide effective support. The accuracy of these contrasting accounts of relationship functioning was evaluated in a study of 102 breast cancer patients and their significant others, interviewed at 4 and 10 months after diagnosis. Results largely confirmed the negative account of relationship functioning. Although significant others provided support in response to patients' physical impairment, they withdrew support in response to patients' emotional distress. Moreover, support from significant others did not alleviate patients' distress or promote physical recovery. These results reveal limits to the effectiveness of close relationships in times of severe stress.