A study was performed examining the influence of preference for trees on self-reported levels of physical, psychological and social wellbeing, mediated by optimism, among 323 students in their final years of high school. Findings indicated that the greater the preference for trees, the greater the individual's optimism, which in turn influenced physical, psychological and social wellbeing. These findings could be important because they pertain to teenagers in school education, residing in a metropolitan area with over four million inhabitants, with a very low ratio of trees to inhabitants. The results could be used in public policy to target this sector of the population in tree planting and environmental education campaigns in ecologically depressed urban areas.