The importance of complete mental health in school context has recently begun to attract a lot of attention. Positive psychology interventions are often associated with improvement in mental health outcomes, but few studies have examined whether story reading is an intervention that is linked with indicators of complete mental health. This study investigated the effects of story reading interventions on both positive and negative indicators of mental health over time for a group of Turkish grade 10 high school students (
n
= 53). These included 33 students in a story reading group and 20 in a control group for comparison. The results showed that story reading led to improvement in students’ mindfulness, optimism, happiness, and positive emotions, and also caused reduction in depression, anxiety, pessimism, and other negative emotions over a 5-week period, with a small to large effect sizes. The obtained results are discussed in the context of their implications for potential psychological interventions in high school settings.