Studies on ICT use in education usually focus on ICT's contribution to training processes. However, scarce research has concentrated on the problematic use of ICT among young people in the school context, and most of it approaches the problem from a psychopathological perspective. The purpose of this paper, in contrast, is to analyse problematic ICT use among young people in their personal and school setting. The methodology involved applying a questionnaire to a sample of 1,052 youths aged between 12 and 18 years old. The study starts with a univariate and bivariate descriptive analysis. Subsequently, three Poisson regression models were developed to evaluate the contribution of several predictor variables to the three types of problematic uses identified in their sphere, learning processes and classroom relationships. Results show a relationship between problematic ICT use in personal and school settings, with older youths who use smartphones (the) most likely to engage in this type of behaviour. The use of mobile technology largely explains the problematic behaviour in the use of ICT among young people in personal and school contexts, which justifies the need to promote actions contributing to more responsible use of this type of technology in all areas of their personal, school and social life.