The current study aimed at investigating the effectiveness of a guidance program based on self-theory in developing leadership behavior skills among middle and late childhood students in the elementary schools in Dhofar Province - Sultanate Oman. The experimental sample consisted of 24 students who were leaders of class, selected purposively. Their ages ranged from 9 to 11 years. They were divided into two equivalent groups: an experimental group and a control group. The study adopted the experimental approach (quasi-experimental design) which has experimental and control groups with a pre-test, post-test and follow-up test. The scale of teachers' assessment of students' leadership behavior skills was used, which consisted of (36) items distributed over four dimensions: responsibility-taking skill, planning skill, teamwork skill, and decision-making skill. The results of the study showed the effectiveness of the guidance program in developing leadership behavior skills. There were no statistically significant differences were found between the post-test and follow-up test for the experimental group, which indicates the sustainability of the effectiveness of the guidance program. Based on the results, the study recommended the adoption of the guiding program in similar studies and with other age groups in all academic levels.