This study looks at the effect of social support mechanisms as potential moderators and mediators of the relationship between stressful acculturation experiences and self-ratings of physical health. Data are from a sample of 3012 Mexican-origin adults aged 18-59 sampled under a probabilistic, stratified, cluster sampling design in Fresno County, California. While acculturation stressors (i.e., discrimination, legal status, and language conflict) all had a gross positive effect on the likelihood of rating oneself in fair/poor health, only legal status stress had a net effect. In addition, greater numbers of peers and family members in the United States, and a higher reliance on religious support mechanisms decreased the likelihood of reporting fair/poor health. However, levels of both instrumental social support and religious support seeking moderated the (nonsignificant, main) effects of discrimination on physical health. This study indicates that physical health is negatively associated with acculturation stressors and positively associated with social support; discrimination is only associated with poorer physical health among those for whom social support is lacking.