Mindfulness is increasingly an important part of clinical case conceptualization and treatment for mental illness. Although links between (1) mindfulness and psychiatric symptoms and (2) mindfulness and functioning are well-established, relatively few studies examine unique contributions of mindfulness to both symptoms and functioning concurrently. Moreover, we found few studies examining mindfulness, symptoms, and functioning using faceted measures of mindfulness. One thousand ninety-nine psychiatric outpatients and 1820 bariatric surgery candidates completed the Five Facet Mindfulness Questionnaire (FFMQ), the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), and the Structured Clinical Interview for DSM-IV (SCID-I), which also included items from the Schedule for Affective Disorders and Schizophrenia (SADS). Pearson correlations suggested four of five mindfulness facets (Observe, Act with Awareness, Nonjudge, Nonreact) related consistently to both psychiatric symptoms and functional outcomes in both the psychiatric and bariatric samples. In the psychiatric sample, Act with Awareness had an indirect effect on functioning, while Nonjudge and Nonreact had both indirect and direct effects on functioning and symptoms. In contrast, the bariatric sample showed direct and indirect effects of Act with Awareness, Nonjudge, and Nonreact on symptoms and functioning, and a single, direct effect of Observe on physical functioning. The fifth facet (Describe) was dropped from both models. Taken together, these results suggest that mindfulness facets vary significantly in their relation to psychiatric symptoms and functioning. Results have implications for conceptualizing mindfulness and mindfulness-based interventions in both clinical and research settings.