There are a number of barriers to trust in the online environment. Despite the awareness of online dangers, young adults take risk on posting personal information on sensitive personal and family information. Trust is crucial to computer mediated communication because there are several applications and transactions that people undertake without coming in contact with each other. Without trust, it could be difficult for such transactions to take effect. Thus, this study was designed to assess the issues of trust in Computer Mediated Communication among students of Canterbury High School, Lagos with particular reference to social networking sites in order to ascertain various challenges encountered and how to guide against negative influences. The following objectives were set out: (i) To assess the extent to which students of Canterbury International High School Ajah- Lekki , Lagos use social networking sites., (ii) to ascertain reasons why students of Canterbury International High School use social networking sites, (iii) to examine the issues of trust arising from the use of social networking among students in Canterbury International High School, Ajah-Lekki, Lagos, (iv) to ascertain the possible ways through which secondary school student can be protected from the negative effects of trust on social networking sites. Uses and Gratification Theory was the Theoretical Frameworks deployed in the study. The study used survey research design which included quantitative and qualitative research methods and also deployed simple random sampling technique to draw population sample comprising S.S. 1, S.S 2 and S. S. 3 students and staff of Canterbury High School. Instruments of data collection included questionnaire and in-depth interview. From the data analysis, it was established that Facebook was the main site frequently visited by students of Canterbury secondary school. Access to the site was mainly through the use of mobile phones and chatting was the main activities that student engaged in. It was further discovered that the issue of trust arising from the use of social networking among students in Canterbury International High School, Lagos included third party privacy, distraction, illicit relations and pornography. The study recommended that there is a need for parents and teachers to caution students about the negative implication of over indulgence on Facebook instead of academic activities and also that there should be restriction of the use of mobile phone both in the school premises and at home.