Objectives: The Gaia program is a 12-week mindfulness intervention based on cultivating body, emotional, and ecological self-awareness, which has been shown to be effective in reducing children's and adolescents' internalizing problems at school. This paper presents the results of a cluster randomized controlled trial aimed at assessing the effectiveness of this program on improving psychological well-being, subjective well-being, and psychological distress in early adolescents. Methods: A sample of 195 early adolescent students (boys, n = 99; girls, n = 96) with a mean age of 11.49 years (standard deviation = 0.80) attending 12 middle school classes participated in the study. Seven Gaia instructors belonging to six schools led the program. Measures were administered at three time points, approximately every 3 months: 1 week before treatment, 1 week after treatment, and 3 months after treatment. We used a multilevel regression model to test whether treatment was effective in increasing psychological well-being and subjective well-being, and reducing psychological distress, as compared to a waiting-list control group. Results: The results showed that the Gaia program improved psychological well-being but not subjective well-being and psychological distress. Specifically, the Gaia program was effective in increasing personal growth and purpose in life, the key eudaimonic components of psychological well-being, in the experimental group whereas they decreased in the control group. Conclusions: Findings from this study provide preliminary evidence that the Gaia program for early adolescents may improve the core eudaimonic components of psychological well-being from pretest to follow-up that, conversely, decrease in the control group.
