Nolen-Hoeksema proposed that rumination increases stressful events and circumstances; however, few studies have examined this question. Thus, we explored whether (a) rumination predicted increases in the generation of chronic and acute stress, (b) excessive reassurance seeking (ERS) mediated links between rumination and stress generation, (c) rumination increased exposure to acute independent (uncontrollable) stress, and (d) rumination predicted chronic stress generation in certain domains, but not others. These questions were examined in a 1-year study of 126 early adolescent girls (M age = 12.39 years) using contextual objective stress interviews. Findings indicated that rumination predicted increases in acute dependent interpersonal stress and chronic interpersonal stress, and ERS mediated these associations. Moreover, rumination was not associated with acute independent stress. Finally, the effect of rumination on chronic stress generation was most salient in adolescents’ romantic lives and in parent-adolescent relationships. These findings suggest that ruminators create stressful interpersonal environments.