There has been rapidly increasing interest over the past decade in the potential of mindfulness-based approaches to psychological and medical treatment, including a recent growth in the area of substance abuse. Thus, the relationship between trait mindfulness and substance use has been explored in several studies. Results, however, have been mixed. While several studies of college student populations have evinced positive correlations between levels of trait mindfulness and substance use, the opposite seems to be true in clinical samples, with multiple studies showing a negative association. The current study reviews research in both non-treatment seeking college students and in clinical samples, and examines the relationship between trait mindfulness and substance dependence in a clinical sample (N = 281). Further, the study assesses the moderating effect of avoidant coping that might explain the disparate findings in the clinical versus nonclinical samples. (C) 2013 Elsevier Ltd. All rights reserved.