The main goal of this article is to present selected results of a comparative study of the use of Internet for buying goods and services in Italy and the United States. Selected hypotheses concerning the diffusion process of the Internet are used to test whether consumption via the web can be explained by the same factors in the two countries. Consequences brought about by the Internet and e-commerce on consumer behaviour are investigated through analysis of available survey data on Italy and the United States. The main finding highlighted in this article is that one of the effects of Internet use is a more rational process of consumption, that takes place in a context where structural (penetration of the Internet, standard demographics), cultural (habit of consumption), and cognitive variables (ability and experience in handling the complexity of the new social space opened up by the Internet) are intertwined and have a role in consumers' decision-making processes. However, this trend toward a more rational and conscious process of consumption is mediated by cultural and institutional factors, which contribute to the social construction of consumption through a more active and informed consumer. The importance of social networks is also emphasised.