The attempts of social network members to regulate individuals’ health behaviors, or health-related social control, is one mechanism by which social relationships influence health. Little is known, however, about whether this process varies in married versus unmarried individuals managing a chronic illness in which health behaviors are a key component. Researchers have proposed that social control attempts may have dual effects on recipients’ well-being, such that improved health behaviors may occur at the cost of increased emotional distress. The current study accordingly sought to examine marital status differences in the sources, frequency, and responses to health-related social control in an ethnically diverse sample of 1477 patients with type 2 diabetes from southern California, USA. Results from two-way ANCOVAs revealed that married individuals reported their spouses most frequently as sources of social control, with unmarried women naming children and unmarried men naming friends/neighbors most frequently as sources of social control. Married men reported receiving social control most often, whereas unmarried men reported receiving social control least often. Regression analyses that examined behavioral and emotional responses to social control revealed that social control using persuasion was associated with better dietary behavior among married patients. Results also revealed a complex pattern of emotional responses, such that social control was associated with both appreciation and hostility, with the effect for appreciation most pronounced among women. Findings from this study highlight the importance of marital status and gender differences in social network members’ involvement in the management of a chronic illness.