The relation between posttraumatic growth (PTG) and aspects of the social context, such as social support and social constraint, continues to be unclear in cancer survivors. Social cognitive processing theory is a useful framework for examining the effect of the social context on PTG. In theory, support interactions may either facilitate or hinder cognitive processing and thus lead to different PTG outcomes. The current study tested the hypothesis that emotional support and instrumental support would each explain a unique amount of the variance in PTG in distressed hematopoietic stem cell transplant (HSCT) survivors. Additionally, it was predicted that social constraint on cancer-related disclosure would be negatively associated with PTG.