This article reports a randomized controlled trial to investigate whether mindfulness training can successfully improve inner peace in participants with no known mental disorder. Fifty-seven participants were randomized to either mindfulness training (n = 29) or wait-list control (n = 28). The experience sampling method was used to measure the fleeting momentary experience of inner peace in participants. In addition, we used an experimental approach to assessing ability to focus attention: the Meditation Breath Attention Score, as well as the self-report Five-Facet Mindfulness Questionnaire (FFMQ). Compared with the wait-list control group, mindfulness training led to an increase in scores of inner peace, Meditation Breath Attention Score and FFMQ, using analysis of repeated measures analysis of variance. Change in inner peace was not, however, mediated by changes in self-rated mindfulness (FFMQ) nor by increased attentional focus. The findings provide first evidence suggesting that using mindfulness training improves the participants' inner peace. The focus here was on the immediate effects and future studies need to use follow-up. © 2013 The Authors. Stress and Health published by John Wiley & Sons Ltd. Mindfulness has been called the 'heart' of Buddhist meditation (Kabat-Zinn, 2003;Thera, 1962), an essential tool to help identify the inner causes of suffering, the possibility of freedom from suffering and the means to realize such freedom (Wallace & Shapiro, 2006). Over the past 30 years, mindfulness has received a great deal of research attention within educational, health and psychiatric settings, because of its demonstrated links to psychological and physical health benefits (Baer, 2003;Keng, Smoski, & Robins, 2011). Mindfulness-based interventions, such as the mindfulness-based stress reduction (MBSR) (Kabat-Zinn, 1990) and mindfulnessbased cognitive therapy (Barnhofer et al., 2009;Segal, Williams, & Teasdale, 2002), have been shown to be successful in alleviating a variety of types of suffering, including reducing pain (Kabat-Zinn, Lipworth, & Burney, 1985;Kabat-Zinn, Lipworth, Burney, & Sellers, 1987;Samuelson, Carmody, Kabat-Zinn, & Bratt, 2007), stress (Astin, 1997), depression (Segal et al., 2002) and anxiety (Delgado et al., 2010). Several studies also demonstrate the benefits of mindfulness-based practice in non-clinical samples. For example, mindfulness training has been shown to improve one's social relationships (Bowen et al., 2006), produce increased positive affect, better immune system responses (Davidson et al., 2003) and better physiological responses to stress and negative emotions (Tang et al., 2009(Tang et al., , 2007. Moreover, mindfulness meditation is associated with changes in grey matter concentration in brain regions involved in emotion regulation (Hölzel et al., 2011).In Buddhism, inner peace is taught as the most important thing in our life. Gautama Buddha described nirvana as the ultimate goal (Mitchell, 2002). Nirvana is an ancient Sanskrit term used in Buddhism to de...