Mindful individuals are able to acknowledge mind wandering and live in the present moment in a nonjudgmental way. Previous studies have found that both mind wandering and mindfulness are associated with subjective well-being. However, the main predictor of happiness is personality; more specifically, happier people are emotionally stable and extraverted. The present study aimed to explore the contribution of the five factors of personality, dispositional mindfulness facets and a mindfulness intervention to happiness. A sample of 372 university students was assessed with the NEO-Five Factor Inventory, and another sample of 217 community adults answered the Big Five Personality Trait Short Questionnaire. Both samples, 589 participants in all, completed the Five Facet Mindfulness Questionnaire and the Subjective Happiness Scale. Furthermore, 55 participants from the general population sample took a 6-week training course in meditation and developing mindfulness. The regression analyses showed that emotional stability and extraversion traits were the strongest predictors of subjective well-being. Nonetheless, the nonjudging facet, which is nonevaluative/acceptance awareness of thoughts and feelings, still remained a significant predictor of happiness when personality was accounted for. Finally, mindfulness training did not increase subjective well-being. Being nonjudgmental of one's inner thoughts, feelings and sensations contributes to happiness even when personality is taken into account. Accordingly, it seems reasonable that mindfulness training that intends to improve subjective well-being should focus on noticing thoughts without judging them.