Researchers have recognized the role of social environment in diabetes management, with substantial attention directed toward spouses or romantic partners of people with diabetes. However, the specific ways in which partners are involved have not been articulated. This study, which included 207 couples in which one person was recently diagnosed with type 2 diabetes, used a mixed-methods approach to assess types of partner involvement in diabetes management. First, different types of partner involvement were qualitatively identified from audiotaped interviews, and links between qualitative findings and demographics were examined. Next, qualitative codes were compared with quantitative measures of partner involvement. Finally, relations of qualitative codes to relationship quality and diabetes outcomes were assessed. Qualitative analyses identified three ways in which partners were involved in diabetes management (support provision, collaboration, and controlling behavior) and two ways in which they were not involved (independent coping and disengagement on the part of the person with diabetes). Participants with diabetes perceived less partner involvement than their partners. Comparisons with quantitative measures revealed that collaboration was distinct from partner support. Reports from participants with diabetes of collaboration, but not partner support, were connected to higher relationship quality and lower A1C, whereas partner reports of collaboration were related to better self-care. Diabetes disengagement was associated with poorer relationship and behavioral outcomes. These findings underscore the varied ways in which partners are and are not involved in diabetes management and suggest that collaboration is more beneficial than social support in terms of relationship quality and diabetes outcomes.