This research investigated the effect of meditation on warning signs of relapse among adults in residential treatment for chemical dependency. Results were that meditation increased participants’ mindfulness, decreased negative mood, and reduced warning signs of relapse. The effect of the intervention on risk of relapse was mediated by mindfulness, the effect of which was, in turn, partially mediated by decrease in negative mood states. The data provide evidence for the effectiveness of meditation to reduce risk for relapse in this population and also add to our knowledge of the relationship between negative mood states and risk for relapse among those in treatment for chemical dependency.