Although it is commonly assumed that social support positively predicts health, the empirical evidence has been inconsistent. We argue that three moderating factors must be considered: (1) support-approving norms (cultural context); (2) support-requiring situations (stressful events); and (3) support-accepting personal style (low neuroticism). Our large-scale cross-cultural survey of Japanese and US adults found significant associations between perceived support and health. The association was more strongly evident among Japanese (from a support-approving cultural context) who reported high life stress (in a support-requiring situation). Moreover, the link between support and health was especially pronounced if these Japanese were low in neuroticism. © 2012 The Author(s).