This study set out to determine the effectiveness of positive thinking intervention on self-discovery of female high school adolescents. This quasi-experimental research had a pretest-posttest, control group design with a follow-up session. The statistical population of the study comprised all female high school students of Arzuiyeh City. Forty girls were selected via convenience sampling method and replaced randomly in control and experimental groups (20 individuals in each group). The research instrument included Akbari Balutbangan and Rezaei's Self-Discovery Scale (2014). The experimental group attended nine 90-minute sessions for two months and the control group received no intervention. Both participating groups completed the Akbari Balutbangan and Rezaei’s Self-Discovery Scale (2014) before the training program, after it, and two months later. The data were analyzed via covariance analysis. The results of univariate and multivariate covariance analysis in the post-test and follow-up phases revealed that the positive thinking intervention had impacted on self-discovery (self-awareness and acceptance, commitment and fascination, transcendence and development, and personal growth) of adolescent girls and promoted these features. Hence, positive psychology training can be used to increase self-discovery (self-awareness and acceptance, commitment and fascination, transcendence and development, and personal growth) of students.