It is increasingly recognised that the internet, in spite of all its benefits to society, can also be correlated with significant harms to individuals and society. Some of these harms have been studied extensively, particularly harms to privacy, harms associated with security and cybercrime, and harms resulting from digital divides. This report covers less studied but equally important harms: harms associated with internet use that concern the health, well-being a functioning of individuals, and the impact on social structures and institutions. The Part I of the study address the issue of the maladaptive use the internet at individual level, including virtual social networks, video games and other potentially addictive types of interactive media content. The three problems which emerged from the study were: generalised internet addiction, online gaming addiction and online gambling addiction. The ultimate aim of the study is to develop concrete policy options to be considered by the EU Institutions and Member States, to mitigate harmful effects of the internet for European citizens. The Part II of the study address the harms of the internet at society level. The harms that are revised are among others: harms to cognitive development, information overload, harmful effects on knowledge and belief and harms to social relationships. The ultimate aim of the study is to develop concrete policy options to be considered by the EU Institutions and Member States, to mitigate harmful effects of the internet for European citizens.