Internet-based commerce is expected to radically affect many consumer markets. Present knowledge of the forthcoming transformations is based largely on the principle of value maximization; in standard economic theories of search, consumers are assumed to be both able and motivated to rationally weigh the costs and benefits they expect to ensue from search. High search costs are offered to explain why consumers evidently do not fully inform themselves about the available options. Electronic media are expected to lower search costs and, thus, radically enhance consumer search. However, little empirical evidence exists in support of these assumptions. The combination of information sources consumers prefer to use is largely unexplored in relation to electronic information sources. Likewise, our knowledge of the objectives related to the procurement decision that leads consumers to adopt electronic sources for product information is still lacking. In this chapter, we examine the determinants of using Internet-based information sources, particularly the World Wide Web.