This study examined the role of intensive mindfulness training on changes in day-to-day experiential processing, psychological symptoms, resilience, and well-being in two groups of community adults (N ¼ 69). Using both quasi-experimental and longitudinal methods, the study found that intensive training, operationalized as 10–12 hours of formal mindfulness practice per day for 1 month, was significantly related to increases in trainingspecific experiential processing capacities, namely trait mindfulness and decentering (reperceiving), in comparison to pre–post-training wait-list controls. In both training groups combined, mindfulness, decentering, and acceptance increased over the pre-training to 1-month follow-up period. Intensive mindfulness training was also related to declines in anxiety and enhanced both subjective well-being and self-compassion from pre-training to follow-up in the two training groups. Finally, increases in trait mindfulness and acceptance were related to improvements in psychological symptoms, well-being, and resilience. Future directions for this novel area of mindfulness research are discussed.