The process of students’ major selection can be influenced due to time and place situations. In this article some influential factors in major selections were investigated. The purpose of his study was to evaluate effective factors in students’ major selection at educational sciences and engineering colleges in University of Tehran. A descriptive survey design method was chosen for this study. Statistical population included all students at educational sciences and engineering colleges in University of Tehran. Using stratified sampling method, 414 individuals were randomly selected. A 44 items researcher made survey instrument was developed to measure students views on major selection factors. Questionnaire’s content validity was evaluated by experts and its reliability was examined through exploratory factor analysis. The reliability of questionnaire via Chronbach's Alpha found to be. 89 Data were analyzed through Mann–Whitney, Friedman and single-sample t tests. Single-sample t-test results indicated that economic (3.99) and individual (3.07) factors had above average impact among engineering students, but social factors (2.18), entrance examination (2.37) and the institutional /education (2.74) had below average effects. Findings indicated that economic factors had less impact on education sciences’ students (2.63), but national entrance examination had above average effects on students’ major selection (3.82).Social factors (3.02), institutional/educational (3.09) and personal (2.91) had a moderate effect. The results of factor analysis identified five factors for engineering students: economical, personal, institutional/educational, entrance exam and social-cultural respectively. Factors identified for educational sciences’ students were: entrance exam, institutional, social-cultural, personal and economical in that order. Furthermore, a significant difference was observed between the two groups in five main factors.