Embodied emotion theory hypothesises a reciprocal relationship between physical expression of emotion and the manner in which emotional information is perceived. The Integrated Cognitive Subsystems (ICS) theory of depression and Mindfulness-Based Interventions (MBIs) propose the body as key in the development and treatment of depression. This study investigated the relationship between posture and outcomes of mindfulness practice; participants meditating in an upright posture were predicted to report greater mindfulness, positive affect and distress tolerance than in a slouched posture. A non-clinical, adult sample (N=39) carried out a 15-minute mindfulness breathing exercise in upright and slouched postures in a counter-balanced within-participant design, with outcome measures of mindfulness, affect and distress tolerance. Participants also reported qualitative experiences. Due to order effects, only data from the first posture participants adopted were analysed, converting the study into a between-participant design. Hypotheses were not supported; between-subjects analyses found no difference in participants’ reported mindfulness, affect or distress tolerance between the two posture groups; potentially due to measurement or power issues. Keeping with previous MBI research, negative affect decreased following the practice in both postures. There was tentative evidence that distress tolerance decreased in the slouched posture condition; although there was no change in the upright condition. Qualitatively, participants reported breathing was easier when upright. These two findings may provide some support for the importance of attending to an upright posture in mindfulness practice. Further research is required to understand the role of the body in depression and MBIs.