The number of children and adolescents accessing the Internet as well as the amount of time online are steadily increasing. The most common online activities include playing video games, accessing web sites, and communicating via chat rooms, email, and instant messaging. A theoretical framework for understanding the effects of Internet use on cognitive development is presented. The proposed framework, based on the cognitive information processing model, the sociocultural perspective, the PASS cognitive processing model, and the neurological orientation, organises previous research in terms of the cognitive consequences of common online activities. From a cognitive-developmental perspective, the Internet is a cultural tool that influences cognitive processes and an environmental stimulus that contributes to the formation of specific cognitive architecture. (Contains 1 figure.)