Adolescents, who are considered the main users of the internet, are not trained on the facilities and correct use of it. On the other hand, they are not skillful in selecting, processing, and analyzing the received information and data. However, the main problem is unfamiliarity of parents and teachers with new communication and information technologies. Therefore, awareness of this weakness can lead us to carefully plan for internet literacy education of parents and teachers. Internet literacy has three layers: first, personal planning on how to use the Internet; second, recognizing characteristics of a message; and third' analysis of the message. The present study has assessed the internet literacy only at its first layer among three main groups; that is, students, their teachers and parents. The participants included 359 Tehran third grade high school students (girls and boys) who were internet users, their teachers (112) and parents (718). They were selected from north, south, east, west, and center of Tehran and a questionnaire was distributed among them to assess their internet literacy. The results showed that only 10.44% of internet user students' parents and 32.31% of their teachers could connect to the internet. Therefore: 1. There was significant differences among students, their teachers and parents in terms of their ability to use internet2. Students used internet more frequently than their teachers and parents3. There were significant differences among students, their teachers and parents in terms of the priority of used internet programs4. There was a not significant difference among students, their teachers and parents in terms of personal planning to use the internet5. 6.58% of students consulted qualified people on how to use the internet.In sum, the three groups (students, their teachers and parents)' differences on the internet literacy levels shows that neither parents, nor teachers are able to train students on how to use the internet and generally are not considered as a reference source for them. Therefore, parents and especially teachers should increase their internet as well as media literacy and their related abilities.