This study focused on the convergent and discriminate validity of the Mathematics Self- Efficacy Informative Sources Scale for high school students. A total number of 692 high school students participated in the study. Both explanatory and confirmatory factor analyses were conducted for the content of the scale. Whether the Mathematics Self-efficacy Informative Sources showed any differences in terms of personal variables such as gender and class level was also examined as part of discriminate validity. According to the results of the factor analyses, the four-factor model of math-inform was supported. According to the distinguished validity results, it would be stated that class level variables were not effective in explaining the variables informative resources. The results were discussed in light of literature and some suggestions were given for further studies.