Optimism can lead to happiness, academic achievement, health, and internal locus of control (Linly & Joseph, 2004, Seligman, 2003, Tailor & Brown, 1998).

This is an interventional study with pretest–posttest control group design. The main purpose of this research is the investigation effectiveness of enhancing of optimism skills on the locus of control in high school students. The main hypothesis of the study was: Enhancing the optimism skills increases the internal locus of control in high school students.

The sample of this study was 40 students randomly selected from high schools of Gorgan city of Iran. Before intervention, two groups completed the pretests of Rutter`s locus of control, Rosenberg`s self–esteem and Oxford happiness questionnaires. Subjects were divided into groups of external and internal locus of control. Externals participated in the training program of optimism skills for 8 sessions. After the intervention, both groups were tested by the same questionnaires again.

Using T-test indicated that the difference between two groups is significant (p<0/007). Results showed that the training program of optimism skills is effective in changing external locus of control into internal. Totally, the result of this study, confirmed the utility and effectiveness of training optimism skills in internalization locus of control in high school students.