Electronic Marketplaces (EMs) have emerged in various industries, supporting the exchange of goods and services of different kinds and promising a huge market potential. However, the rapid rise and sharp fall of EMs within a few short years raises the question about EM usage. Although EMs represent a fast growing segment, firms are still reluctant to utilize them. This book represents one of the first large-scale empirical efforts to explore the EM usage from the buyer perspective. The author developed a research model proposing four primary factors that affect the extent of EM usage: expected benefits and perceived risks of EMs, purchasing situation, and e-business readiness. A large-scale survey was conducted in USA and yielded 359 responses from purchasing managers. The research findings indicated that there is a positive relationship between expected benefits and extent of EM usage, there is a negative relationship between perceived risks and extent of EM usage, and there is a positive relationship between purchasing situation and extent of EM usage. Important theoretical as well as practical implications of this research are also discussed.