This study examined differences in understanding the technical and social complexity of the Internet across four age groups, 5-8-year-olds, 9-10-year-olds, 11-12-year-olds, and adults. The major findings indicated overall age differences in understanding across the four groups, particularly between 9-10- and 11-12-year-olds, and fewer differences based on Internet experience. These findings are discussed with respect to their implications for protecting children online and advancing their development in the Internet age.