While support continues to mount for the effectiveness of mindfulness training in improving psychological functioning, researchers are only beginning to examine its mechanisms of action. The present study employed multimodal assessment of the experience and regulation of emotion to examine the effects of a brief mindfulness intervention. Seventy undergraduate students at a small southern state university were randomly assigned to listen to a 15-min recording of either a mindfulness intervention or neutral recording followed by either a positive or negative emotion induction. At the completion of the intervention mindfulness participants demonstrated greater mindfulness than the control group as indicated by greater self-reported state mindfulness, greater Left > Right frontal brain asymmetry, and greater heart rate variability. Further, participants receiving the mindfulness intervention experienced greater emotional awareness, indicated by reporting higher positive affect regardless of emotion induction and higher negative affect when experiencing a negative emotion induction. Participants who experienced a negative emotion induction after the mindfulness intervention also reported feeling more overwhelmed and unable to improve their emotional state, suggesting that brief mindfulness intervention was successful in reducing emotional avoidance, but failed to improve the ability to regulate emotion sufficiently to withstand the demands of an aversive emotional experience. These results have significant clinical implications, as they suggest that individuals may feel more dysregulated when experiencing negative stimuli and/or mood in the beginning stages of mindfulness practice.