Introduction: Creativity is flexibility in thinking, being full of ideas, the ability to cope with new ideas and discover new connections between available items. Also, assertiveness is an important social skill during the development of a teenager. Considering rapid changes of today's world, only those, who can adapt to change, survive. The aim of this researeh was to study the effect of problem solving skills training on creativity and assertiveness among high school students in Shush city.

Methods: This quasi-experimental study was done with pretest-posttest on all male students in the second year of high school in the city of Shush during years 2013 and 2014. The sample was selected using multistage random cluster sampling (even and odd design), and randomly assigned to two 20-member experimental and control groups. The measurement tool was the 60-point Abedi creativity Standard questionnaire and 33-point ASA assertiveness questionnaire. To carry out the research, pre-test was taken in both experimental and control groups. The experimental group received eight sessions (90 minutes in duration) about problem solving skills training while the control group did not receive any intervention. For data analysis, the SPSS-18 software and multivariate covariance were used.

Results: The results indicated that there was a significant difference between experimental and control groups in creativity and assertiveness (P < 0.001). The rate of creativity and assertiveness in the experimental group was singnificantly higher compared with the control group.

Conclusions: Considering the importance of variables such as creativity and self-expression, it is necessary to provide continuous training during school years, to enhance the quality of education.