OBJECTIVES: The aim of this study was to investigate the relationship between internet addiction, smartphone addiction, and psychosocial factors. This study was designed to examine the vulnerability factors for internet and smartphone addiction. METHODS: The participants were 1041 children and adolescents in a small and medium-sized cities. All of the participants were evaluated in terms of their demographic characteristics and present use of the internet and smartphone, as well as using internet and smartphone addiction and other psychological scales. Statistical analyses were performed to compare the psychosocial factors between the high risk, potential risk, and general user groups of internet and smartphone addiction. RESULTS: The participants were classified into three groups, the high risk (N=33), potential risk (N=203), and general user (N=805) groups with regard to their internet and smartphone addiction level. There were statistical significantly differences between the groups in terms of the economic status of the family, academic performance, parents, use of internet and smartphone, loneliness, family cohesion, family adaptability, perceived social support, and peer relationship. CONCLUSION: These results suggest that the internet and smartphone addiction of children and adolescents is related to various psychosocial vulnerability factors.