This study investigated the effects of rumination on indecision, assessed as high levels of perceived decision difficulty, low confidence in a decision, and decision latency. Dysphoric and nondysphoric participants were assigned to either a rumination or a distraction induction. Subsequently, they made four decisions with alleged real-life consequences. As predicted, rumination exhibited a negative effect on dysphoric participants' decision-making process. They experienced the decisions as more difficult and had less confidence in their choices. No effects emerged on the measure of decision time. Mediation analyses revealed that increased difficulty of the decisions was due to self-focused thinking as a cognitive consequence of rumination, while reduced confidence in the decisions was partly mediated by negative affect that resulted from rumination. The finding that rumination affects the important life domain of decision making by fostering indecision in dysphoric individuals is a central extension of previous studies on rumination's consequences. In addition, these results provide insight into the depressive symptom of indecisiveness by revealing its underlying mechanisms. © 2009 Wiley Periodicals, Inc. J Clin Psychol 66: 229–248, 2010.