The aim of this study was to predict the tendency to high-risk behaviors based on psychological flexibility and attachment styles in male and female high school students. This research was applied in terms of purpose, and descriptive and correlational in terms of data collection. The statistical population of this study was all high school students in the academic year 2020-2021. Using cluster random sampling method, 300 people were selected as a sample. At the descriptive statistics level, the mean, standard deviation, minimum and maximum scores, and at the inferential statistics level, Pearson coefficient and multiple regression have been calculated. The results indicated that the flexibility and secure attachment had a negative and significant relationship with the tendency to high-risk behavior and the avoidant attachment. Moreover, it was indicated that ambivalent attachment had a positive and significant relationship with the tendency to high-risk behavior. Also flexibility (p <0.05, β = -0.17), secure attachment style (p <0.05, β = -0.19), avoidance attachment style (p <0.05, = 0.18) β) and ambivalent attachment style (p <0.05, β = 0.13) were significant predictors of the tendency to high-risk behavior.