This study is an empirical analysis of the Internet business models used by United States firms that filed for initial public sale of securities from 1996 thru 2001. Analysis included identification of the business modes deployed for generating revenue from the Internet, extension of Eisenmann’s [2002] classifications of Internet business models and the matching of firms to the extended classifications. The analysis revealed that Internet companies comprise a significant portion of the emerging U. S. economy. Further, a significant percentage of traditional companies derive material revenue from the Internet. The results also suggested that there is a significant differentiation of Internet business models. Finally, the results expand the definition of an Internet firm to include firms that are not limited to direct service-related functions described by Eisenmann. In fact, numerous firms derive their existence by providing services, hardware or software that supports the Internet sales and services of other firms.