This dissertation examined the moderating role of self-regulatory capacity, as indexed by respiratory sinus arrhythmia (RSA), in mitigating the negative interpersonal consequences of rumination. Interpersonal emotion regulation theory suggests that the social context in which intrapersonal emotion regulation strategies are enacted will impact the outcomes of those strategies. Within this frame, RSA was examined as both an intrapersonal and interpersonal moderator of the negative interpersonal impact of rumination. In manuscript 1, it was found that greater rumination and lower RSA were associated with worse interpersonal outcomes, including more negative interpersonal behaviors, impaired support mobilization, and interpersonal stress. Therefore, the hypothesis that RSA acts as an intrapersonal regulatory factor associated with the negative interpersonal consequences of ruminating was supported. In manuscript 2, the association of rumination with marital conflict was attenuated when the romantic partner had higher RSA. Here, the reciprocal hypothesis was supported, in that romantic partners with greater self-regulatory capacity reduced the negative interpersonal impact of rumination within romantic relationships. Together, the findings suggest that rumination negatively impacts the social environment, that the social environment modulates the negative interpersonal consequences of rumination, and that greater RSA acts as both an intrapersonal and interpersonal moderator of these effects.