There is no doubt that Information and Communication Technologies (ICT) are now an integral part of the life of children and young people. Some of the recent literature studies on literacy in ICT show that this should incorporate Internet literacy, Computer literacy and Information literacy, and being these three forms of literacy indispensable in many aspects of human life in the 21st century. To determine the relationships between these three dimensions of literacy in ICT, the importance of parental and teachers support and use of the Internet as a pedagogical tool, as well as the influence of these factors on school performance and assess how they relate to explain, in general, why ICT literacy influences school performance, structural equation models have been used. The results show that ICT literacy is undoubtedly a factor in school performance of students of the 3rd cycle of basic education and secondary education (7th to 12th grades) in the district of Vila Real, Portugal. It was further found that the use of the Internet as a pedagogical tool is a major factor in school performance, and that parental and teacher support has a positive influence on ICT literacy.