The main objective of this study was to examine the effects of hidden curriculum on gifted students’ sociability in Tehran. The study was carried out in 2013-2014 academic year. In this applied research the research design was descriptive-correlational. The instrumentation comprised a 70-item researcher-made questionnaire whose validity was approved by specialists and whose validity was calculated to be 0.78 using Cronbach’s alpha. The population of the study and the sample size comprised 4528 and 360 students, respectively. For the purpose of data analysis Pearson correlation coefficient, comparison of means, and one-way analysis of variance were utilized. Results indicated that there was a significant relationship between students’ sociability and the schools’ norms and values. In addition, a reverse association was found between students’ sociability and the teacher-principal-parent relations. The relations among teachers as well as the relations among parents did not have much influence on students’ sociability. However, a significant association was observed between relationships among students and their sociability. Furthermore, a relatively weak association was found between gifted student’s attitude toward their giftedness label and their sociability.