In "The Information Age: Economy, Society, and Culture," sociologist Manuel Castells argues that information and communication technologies are associated with a new kind of economy, society, and culture that he calls "informationalism." In this new economic order, knowledge generation, information processing, and symbolic communication--"the action of knowledge on knowledge"--are the main sources of productivity and profit. The commanding heights of the new economy (though not the whole of it) have become global: information and communication technologies make possible for the first time in human history an economy that operates in real time on a planetary scale through computer-based financial transactions. Castells' views are discussed in this article.